title: UGM-27 Polaris

text: In the mid-1950s the Navy was involved in the Jupiter missile project with the U.S. Army, and had influenced the design by making it squat so it would fit in submarines. However, they had concerns about the use of liquid fuel rockets on board ships, and some consideration was given to a solid fuel version, Jupiter S. In 1956, during an anti-submarine study known as Project Nobska, Edward Teller suggested that very small hydrogen bomb warheads were possible. A crash program to develop a missile suitable for carrying such warheads began as Polaris, launching its first shot less than four years later, in February 1960.


title: UGM-27 Polaris

text: As the Polaris missile was fired underwater from a moving platform, it was essentially invulnerable to counterattack. This led the Navy to suggest, starting around 1959, that they be given the entire nuclear deterrent role. This led to new infighting between the Navy and the U.S. Air Force, the latter responding by developing the counterforce concept that argued for the strategic bomber and ICBM as key elements in flexible response. Polaris formed the backbone of the U.S. Navy's nuclear force aboard a number of custom-designed submarines. In 1963, the Polaris Sales Agreement led to the Royal Navy taking over the United Kingdom's nuclear role, and while some tests were carried out by the Italian Navy, this did not lead to use.


title: UGM-27 Polaris

text: The Polaris missile was gradually replaced on 31 of the 41 original SSBNs in the U.S. Navy by the MIRV-capable Poseidon missile beginning in 1972. During the 1980s, these missiles were replaced on 12 of these submarines by the Trident I missile. The 10 - and SSBNs retained Polaris A-3 until 1980 because their missile tubes were not large enough to accommodate Poseidon. With beginning sea trials in 1980, these submarines were disarmed and redesignated as attack submarines to avoid exceeding the SALT II strategic arms treaty limits.


title: UGM-27 Polaris

text: The Polaris missile program's complexity led to the development of new project management techniques, including the Program Evaluation and Review Technique (PERT) to replace the simpler Gantt chart methodology.


title: UGM-27 Polaris

text: The Polaris missile replaced an earlier plan to create a submarine-based missile force based on a derivative of the U.S. Army Jupiter Intermediate-range ballistic missile. Chief of Naval Operations Admiral Arleigh Burke appointed Rear Admiral W. F. "Red" Raborn as head of a Special Project Office to develop Jupiter for the Navy in late 1955. The Jupiter missile's large diameter was a product of the need to keep the length short enough to fit in a reasonably-sized submarine. At the seminal Project Nobska conference in 1956, with Admiral Burke present, nuclear physicist Edward Teller stated that a physically small one-megaton warhead could be produced for Polaris within a few years, and this prompted Burke to leave the Jupiter program and concentrate on Polaris in December of that year. Polaris was spearheaded by the Special Project Office's Missile Branch under Rear Admiral Roderick Osgood Middleton, and is still under the Special Project Office. Admiral Burke later was instrumental in determining the size of the Polaris submarine force, suggesting that 40-45 submarines with 16 missiles each would be sufficient. Eventually, the number of Polaris submarines was fixed at 41.


title: UGM-27 Polaris

text: The was the first submarine capable of deploying U.S. developed submarine-launched ballistic missiles (SLBM). The responsibility of the development of SLBMs was given to the Navy and the Army. The Air Force was charged with developing a land-based intermediate range ballistic missile (IRBM), while an IRBM which could be launched by land or by sea was tasked to the Navy and Army. The Navy Special Projects (SP) office was at the head of the project. It was led by Rear Admiral William Raborn.


title: UGM-27 Polaris

text: On September 13, 1955, James R. Killian, head of a special committee organized by President Eisenhower, recommended that both the Army and Navy come together under a program aimed at developing an intermediate-range ballistic missile (IRBM). The missile, later known as Jupiter, would be developed under the Joint Army-Navy Ballistic Missile Committee approved by Secretary of Defense Charles E. Wilson in early November of that year. The first IRBM boasted a liquid-fueled design. Liquid fuel is compatible with aircraft; it was considered less compatible with submarines in the West, even though in the Soviet Navy liquid-fuelled SLBMs, none of which used cryogenic components, were in overwhelming majority, and R-29RMU2 is still in service with the Russian Navy (it's expected to be phased out after 2030). Solid fuels, on the other hand, make logistics and storage simpler and are safer. Not only was the Jupiter a liquid fuel design, it was also very large; even after it was designed for solid fuel, it was still a whopping 160,000 pounds. A smaller, new design would weigh much less, estimated at 30,000 pounds. The Navy would rather develop a smaller, more easily manipulated design. Edward Teller was one of the scientists encouraging the progress of smaller rockets. He argued that the technology needed to be discovered, rather than apply technology that is already created. Raborn was also convinced he could develop smaller rockets. He sent officers to make independent estimates of size to determine the plausibility of a small missile; while none of the officers could agree on a size, their findings were encouraging nonetheless.


title: UGM-27 Polaris

text: The U.S. Navy began work on nuclear-powered submarines in 1946. They launched the first one, the USS Nautilus in 1955. Nuclear powered submarines were the least vulnerable to a first strike from the Soviet Union. The next question that led to further development was what kind of arms the nuclear-powered submarines should be equipped with. In the summer of 1956, the navy sponsored a study by the National Academy of Sciences on anti-submarine warfare at Nobska Point in Woods Hole, Massachusetts, known as Project NOBSKA. The navy's intention was to have a new missile developed that would be lighter than existing missiles and cover a range up to fifteen hundred miles. A problem that needed to be solved was that this design would not be able to carry the desired one-megaton thermonuclear warhead.


title: UGM-27 Polaris

text: This study brought Edward Teller from the recently formed nuclear weapons laboratory at Livermore and J. Carson Mark, representing the Los Alamos nuclear weapons laboratory. Teller was already known as a nuclear salesman, but this became the first instance where there was a big betting battle where he outbid his Los Alamos counterpart. The two knew each other well: Mark was named head of the theoretical division of Los Alamos in 1947, a job that was originally offered for Teller. Mark was a cautious physicist and no match for Teller in a bidding war.


title: UGM-27 Polaris

text: At the NOBSKA summer study, Edward Teller made his famous contribution to the FBM program. Teller offered to develop a lightweight warhead of one-megaton strength within five years. He suggested that nuclear-armed torpedoes could be substituted for conventional ones to provide a new anti-submarine weapon. Livermore received the project. When Teller returned to Livermore, people were astonished by the boldness of Teller's promise. It seemed inconceivable with the current size of nuclear warheads, and Teller was challenged to support his assertion. He pointed out the trend in warhead technology, which indicated reduced weight to yield ratios in each succeeding generation. When Teller was questioned about the application of this to the FBM program, he asked, ‘Why use a 1958 warhead in a 1965 weapon system?’


title: UGM-27 Polaris

text: Mark disagreed with Teller's prediction that the desired one-megaton warhead could be made to fit the missile envelope within the timescale envisioned. Instead, Mark suggested that half a megaton would be more realistic and he quoted a higher price and a longer deadline. This simply confirmed the validity of Teller's prediction in the Navy's eyes. Whether the warhead was half or one megaton mattered little so long as it fitted the missile and would be ready by the deadline. Almost four decades later, Teller said, referring to Mark's performance, that it was “an occasion when I was happy about the other person being bashful.”


title: UGM-27 Polaris

text: When the Atomic Energy Commission backed up Teller's estimate in early September, Admiral Burke and the Navy Secretariat decided to support SPO in heavily pushing for the new missile, now named Polaris by Admiral Raborn.


title: UGM-27 Polaris

text: There is a contention that the Navy's "Jupiter" missile program was unrelated to the Army program. The Navy also expressed an interest in Jupiter as an SLBM, but left the collaboration to work on their Polaris. At first, the newly assembled SPO team had the problem of making the large, liquid-fuel Jupiter IRBM work properly. Jupiter retained the short, squat shape intended to fit in naval submarines. Its sheer size and volatility of its fuel made it very unsuited to submarine launching and was only slightly more attractive for deployment on ships. The missile continued to be developed by the Army's German team in collaboration with their main contractor, Chrysler Corporation. SPO's responsibility was to develop a sea-launching platform with necessary fire control and stabilization systems for that very purpose. The original schedule was to have a ship-based IRBM system ready for operation evaluation by January 1, 1960, and a submarine-based one by January 1, 1965.


title: UGM-27 Polaris

text: However, the Navy was deeply dissatisfied with the liquid fuel IRBM. The first concern was that the cryogenic liquid fuel was not only extremely dangerous to handle, but launch-preparations were also very time-consuming. Second, an argument was made that liquid-fueled rockets gave relatively low initial acceleration, which is disadvantageous in launching a missile from a moving platform in certain sea states. By mid-July 1956, the Secretary of Defense's Scientific Advisory Committee had recommended that a solid-propellant missile program be fully instigated but not using the unsuitable Jupiter payload and guidance system.


title: UGM-27 Polaris

text: By October 1956, a study group comprising key figures from Navy, industry and academic organizations considered various design parameters of the Polaris system and trade-offs between different sub-sections. The estimate that a 30,000-pound missile could deliver a suitable warhead over 1500 nautical miles was endorsed. With this optimistic assessment, the Navy now decided to scrap the Jupiter program altogether and sought out the Department of Defense to back a separate Navy missile.


title: UGM-27 Polaris

text: A huge surfaced submarine would carry four "Jupiter" missiles, which would be carried and launched horizontally. This was probably the never-built SSM-N-2 Triton program. However, a history of the Army's Jupiter program states that the Navy was involved in the Army program, but withdrew at an early stage.


title: UGM-27 Polaris

text: Originally, the Navy favored cruise missile systems in a strategic role, such as the Regulus missile deployed on the earlier and a few other submarines, but a major drawback of these early cruise missile launch systems (and the Jupiter proposals) was the need to surface, and remain surfaced for some time, to launch. Submarines were very vulnerable to attack during launch, and a fully or partially fueled missile on deck was a serious hazard. The difficulty of preparing a launch in rough weather was another major drawback for these designs, but rough sea conditions did not unduly affect Polaris' submerged launches.


title: UGM-27 Polaris

text: It quickly became apparent that solid-fueled ballistic missiles had advantages over cruise missiles in range and accuracy, and could be launched from a submerged submarine, improving submarine survivability.


title: UGM-27 Polaris

text: The prime contractor for all three versions of Polaris was Lockheed Missiles and Space Company (now Lockheed Martin).


title: UGM-27 Polaris

text: The Polaris program started development in 1956. , the first U.S. missile submarine, successfully launched the first Polaris missile from a submerged submarine on July 20, 1960. The A-2 version of the Polaris missile was essentially an upgraded A-1, and it entered service in late 1961. It was fitted on a total of 13 submarines and served until June 1974. Ongoing problems with the W-47 warhead, especially with its mechanical arming and safing equipment, led to large numbers of the missiles being recalled for modifications, and the U.S. Navy sought a replacement with either a larger yield or equivalent destructive power. The result was the W-58 warhead used in a "cluster" of three warheads for the Polaris A-3, the final model of the Polaris missile.


title: UGM-27 Polaris

text: One of the initial problems the Navy faced in creating an SLBM was that the sea moves, while a launch platform on land does not. Waves and swells rocking the boat or submarine, as well as possible flexing of the ship's hull, had to be taken into account to properly aim the missile.


title: UGM-27 Polaris

text: The Polaris development was kept on a tight schedule and the only influence that changed this was the USSR's launching of SPUTNIK on October 4, 1957. This caused many working on the project to want to accelerate development. The launch of a second Russian satellite and pressing public and government opinions caused Secretary Wilson to move the project along more quickly.


title: UGM-27 Polaris

text: The Navy favored an underwater launch of an IRBM, although the project began with an above-water launch goal. They decided to continue the development of an underwater launch, and developed two ideas for this launch: wet and dry. Dry launch meant encasing the missile in a shell that would peel away when the missile reached the water's surface. Wet launch meant shooting the missile through the water without a casing. While the Navy was in favor of a wet launch, they developed both methods as a failsafe. They did this with the development of gas and air propulsion of the missile out of the submerged tube as well.


title: UGM-27 Polaris

text: The first Polaris missile tests were given the names “AX-#” and later renamed “A1X-#”. Testing of the missiles occurred:


title: UGM-27 Polaris

text: It was in between these two tests that the inertial guidance system was developed and implemented for testing.


title: UGM-27 Polaris

text: At the time that the Polaris project went live, submarine navigation systems accuracy was adequate for existing weapons systems. Initially, developers of Polaris were set to utilize the existing 'Stable Platform' configuration of the inertial guidance system. Created at the MIT Instrumentation Laboratory, this Ships Inertial Navigation System (SINS) was supplied to the Navy in 1954. The developers of Polaris encountered many issues from the birth of the project, however, perhaps the most unsettling for them was the outdated technology of the gyroscopes they would be implementing.


title: UGM-27 Polaris

text: This 'Stable Platform' configuration did not account for the change in gravitational fields that the submarine would experience while it was in motion, nor did it account for the ever-altering position of the Earth. This problem raised many concerns, as this would make it nearly impossible for navigational read outs to remain accurate and reliable. A submarine equipped with Ballistic Missiles was of little to no use if operators had no way to direct them. Polaris was thus forced to seek elsewhere and quickly found hope in a guidance system that had been abandoned by the U.S. Air Force. The Autonetics Division of North American Aviation had previously been faced with the task of developing a guidance system for the U.S. Air Force Navaho known as the XN6 Autonavigator. The XN6 was a system designed for air-breathing Cruise missiles, but by 1958 had proved useful for installment on submarines.


title: UGM-27 Polaris

text: A predecessor to the GPS satellite navigation system, the Transit system (later called NAVSAT), was developed because the submarines needed to know their position at launch in order for the missiles to hit their targets. Two American physicists, William Guier and George Weiffenbach, at Johns Hopkins's Applied Physics Laboratory (APL), began this work in 1958. A computer small enough to fit through a submarine hatch was developed in 1958, the AN/UYK-1. It was used to interpret the Transit satellite data and send guidance information to the Polaris, which had its own guidance computer made with ultra miniaturized electronics, very advanced for its time, because there wasn't much room in a Polaris—there were 16 on each submarine. The Ship's Inertial Navigation System (SINS) was developed earlier to provide a continuous dead reckoning update of the submarine's position between position fixes via other methods, such as LORAN. This was especially important in the first few years of Polaris, because Transit was not operational until 1964. By 1965 microchips similar to the Texas Instruments units made for the Minuteman II were being purchased by the Navy for the Polaris. The Minuteman guidance systems each required 2000 of these, so the Polaris guidance system may have used a similar number. To keep the price under control, the design was standardized and shared with Westinghouse Electric Company and RCA. In 1962, the price for each Minuteman chip was $50. The price dropped to $2 in 1968.


title: UGM-27 Polaris

text: This missile replaced the earlier A-1 and A-2 models in the U.S. Navy, and also equipped the British Polaris force. The A-3 had a range extended to and a new weapon bay housing three Mk 2 re-entry vehicles (ReB or Re-Entry Body in U.S. Navy and British usage); and the new W-58 warhead of 200 kt yield. This arrangement was originally described as a "cluster warhead" but was replaced with the term Multiple Re-Entry Vehicle (MRV). The three warheads, also known as "bomblets", were spread out in a "shotgun" like pattern above a single target and were not independently targetable (such as a MIRV missile is). The three warheads were stated to be equivalent in destructive power to a single one-megaton warhead due to their spread out pattern on the target. The first Polaris submarine outfitted with MRV A-3's was the USS "Daniel Webster" in 1964. Later the Polaris A-3 missiles (but not the ReBs) were also given limited hardening to protect the missile electronics against nuclear electromagnetic pulse effects while in the boost phase. This was known as the A-3T ("Topsy") and was the final production model.


title: UGM-27 Polaris

text: The initial test model of the Polaris was referred to as the AX series and made its maiden flight from Cape Canaveral on September 24, 1958. The missile failed to perform its pitch and roll maneuver and instead just flew straight up, however the flight was considered a partial success (at that time, "partial success" was used for any missile test that returned usable data). The next flight on October 15 failed spectacularly when the second stage ignited on the pad and took off by itself. Range Safety blew up the errant rocket while the first stage sat on the pad and burned. The third and fourth tests (December 30 and January 9) had problems due to overheating in the boattail section. This necessitated adding extra shielding and insulation to wiring and other components. When the final AX flight was conducted a year after the program began, 17 Polaris missiles had been flown of which five met all of their test objectives.


title: UGM-27 Polaris

text: The first operational version, the Polaris A-1, had a range of and a single Mk 1 re-entry vehicle, carrying a single W-47-Y1 600 kt nuclear warhead, with an inertial guidance system which provided a circular error probable (CEP) of . The two-stage solid propellant missile had a length of , a body diameter of , and a launch weight of .


title: UGM-27 Polaris

text: Work on its W47 nuclear warhead began in 1957 at the facility that is now called the Lawrence Livermore National Laboratory by a team headed by John Foster and Harold Brown. The Navy accepted delivery of the first 16 warheads in July 1960. On May 6, 1962, a Polaris A-2 missile with a live W47 warhead was tested in the "Frigate Bird" test of Operation Dominic by in the central Pacific Ocean, the only American test of a live strategic nuclear missile.


title: UGM-27 Polaris

text: The two stages were both steered by thrust vectoring. Inertial navigation guided the missile to about a 900 m (3,000-foot) CEP, insufficient for use against hardened targets. They were mostly useful for attacking dispersed military surface targets (airfields or radar sites), clearing a pathway for heavy bombers, although in the general public perception Polaris was a strategic second-strike retaliatory weapon.


title: UGM-27 Polaris

text: To meet the need for greater accuracy over the longer ranges the Lockheed designers included a reentry vehicle concept, improved guidance, fire control, and navigation systems to achieve their goals. To obtain the major gains in performance of the Polaris A3 in comparison to early models, there were many improvements, including propellants and material used in the construction of the burn chambers. The later versions (the A-2, A-3, and B-3) were larger, weighed more, and had longer ranges than the A-1. The range increase was most important: The A-2 range was , the A-3 , and the B-3 . The A-3 featured multiple re-entry vehicles (MRVs) which spread the warheads about a common target, and the B-3 was to have penetration aids to counter Soviet Anti-Ballistic Missile defenses.


title: UGM-27 Polaris

text: The U.S. Navy began to replace Polaris with Poseidon in 1972. The B-3 missile evolved into the C-3 Poseidon missile, which abandoned the decoy concept in favor of using the C3's greater throw-weight for larger numbers (10–14) of new hardened high-re-entry-speed reentry vehicles that could overwhelm Soviet defenses by sheer weight of numbers, and its high speed after re-entry. This turned out to be a less than reliable system and soon after both systems were replaced by the Trident. A proposed Undersea Long-Range Missile System (ULMS) program outlined a long-term plan which proposed the development of a longer-range missile designated as ULMS II, which was to achieve twice the range of the existing Poseidon (ULMS I) missile. In addition to a longer-range missile, a larger submarine (Ohio-class) was proposed to replace the submarines currently being used with Poseidon. The ULMS II missile system was designed to be retrofitted to the existing SSBNs, while also being fitted to the proposed Ohio-class submarine.


title: UGM-27 Polaris

text: In May 1972, the term ULMS II was replaced with Trident. The Trident was to be a larger, higher-performance missile with a range capacity greater than 6000 miles. Under the agreement, the United Kingdom paid an additional 5% of their total procurement cost of 2.5 billion dollars to the U.S. government as a research and development contribution.


title: UGM-27 Polaris

text: In 2002, the United States Navy announced plans to extend the life of the submarines and the D5 missiles to the year 2040. This requires a D5 Life Extension Program (D5LEP), which is currently underway. The main aim is to replace obsolete components at minimal cost by using commercial off the shelf (COTS) hardware; all the while maintaining the demonstrated performance of the existing Trident II missiles.


title: UGM-27 Polaris

text: STARS, a strategic targeting system, is a BMDO program managed by the U. S. Army Space and Strategic Defense Command (SSDC). It began in 1985 in response to concerns that the supply of surplus Minuteman I boosters used to launch targets and other experiments on intercontinental ballistic missile flight trajectories in support of the Strategic Defense Initiative would be depleted by 1988. SSDC tasked Sandia National Laboratories, a Department of Energy laboratory, to develop an alternative launch vehicle using surplus Polaris boosters. The Sandia National Laboratories developed two STARS booster configurations: STARS I and STARS II.


title: UGM-27 Polaris

text: commercially procured Orbis I third stage. It can deploy single or multiple payloads, but the multiple payloads cannot be deployed in a manner that simulates the operation of a post-boost vehicle. To meet this specific need, Sandia developed an Operations and Deployment


title: UGM-27 Polaris

text: Experiments Simulator (ODES), which functions as a PBV. When ODES was added to STARS I, the configuration became known as STARS II. The development phase of the STARS program was completed in 1994, and BMDO provided about $192.1 million for this effort. The operational phase began in 1995. The first STARS I flight, a hardware check-out flight, was launched in February 1993, and the second flight, a STARS I reentry vehicle experiment, was launched in August 1993.


title: UGM-27 Polaris

text: The third flight, a STARS II development mission, was launched in July 1994, with all three flights considered to be successful by BMDO. The Secretary of Defense conducted a comprehensive review in 1993 of the nation's defense strategy, which drastically reduced the number of STARS launches required to support National Missile Defense (NMD)2 and BMDO funding. Due to the launch and budget reductions, the STARS office developed a draft long-range plan for the STARS program. The study examined three options:


title: UGM-27 Polaris

text: When the STARS program was started in 1985 it was perceived that there would be four launches per year. Because of the large number of anticipated launches and an unknown defect rate for surplus Polaris motors, the STARS office acquired 117 first-stage and 102 second-stage surplus motors. As of December 1994, seven first-stage and five second-stage refurbished motors were available for future launches. BMDO is currently evaluating STARS as a potential long-range system for launching targets for development tests of future Theater Missile Defense 3 systems. STARS I was first launched in 1993, and from 2004 onwards has served as the standard booster for trials of the Ground-Based Interceptor.


title: UGM-27 Polaris

text: From the early days of the Polaris program, American senators and naval officers suggested that the United Kingdom might use Polaris. In 1957 Chief of Naval Operations Arleigh Burke and First Sea Lord Louis Mountbatten began corresponding on the project. After the cancellations of the Blue Streak and Skybolt missiles in the 1960s, under the 1962 Nassau Agreement that emerged from meetings between Harold Macmillan and John F. Kennedy, the United States would supply Britain with Polaris missiles, launch tubes, ReBs, and the fire-control systems. Britain would make its own warheads and initially proposed to build five ballistic missile submarines, later reduced to four by the incoming Labour government of Harold Wilson, with 16 missiles to be carried on each boat. The Nassau Agreement also featured very specific wording. The intention of wording the agreement in this manner was to make it intentionally opaque. The sale of the Polaris was malleable in how an individual country could interpret it due to the diction choices taken in the Nassau Agreement. For the United States of America, the wording allowed for the sale to fall under the scope of NATO's deterrence powers. On the other hand, for the British, the sale could be viewed as a solely British deterrent. The Polaris Sales Agreement was signed on April 6, 1963.


title: UGM-27 Polaris

text: In return, the British agreed to assign control over their Polaris missile targeting to the SACEUR (Supreme Allied Commander, Europe), with the provision that in a national emergency when unsupported by the NATO allies, the targeting, permission to fire, and firing of those Polaris missiles would reside with the British national authorities. Nevertheless, the consent of the British Prime Minister is and has always been required for the use of British nuclear weapons, including SLBMs.


title: UGM-27 Polaris

text: The operational control of the Polaris submarines was assigned to another NATO Supreme Commander, the SACLANT (Supreme Allied Commander, Atlantic), who is based near Norfolk, Virginia, although the SACLANT routinely delegated control of the missiles to his deputy commander in the Eastern Atlantic area, COMEASTLANT, who was always a British admiral.


title: UGM-27 Polaris

text: Polaris was the largest project in the Royal Navy's peacetime history. Although in 1964 the new Labour government considered cancelling Polaris and turning the submarines into conventionally armed hunter-killers, it continued the program as Polaris gave Britain a global nuclear capacity—perhaps east of Suez—at a cost £150 million less than that of the V bomber force. By adopting many established, American, methodologies and components Polaris was finished on time and within budget. On 15 February 1968, , the lead ship of her class, became the first British vessel to fire a Polaris. All Royal Navy SSBNs have been based at Faslane, only a few miles from Holy Loch. Although one submarine of the four was always in a shipyard undergoing a refit, recent declassifications of archived files disclose that the Royal Navy deployed four boatloads of reentry vehicles and warheads, plus spare warheads for the Polaris A3T, retaining a limited ability to re-arm and put to sea the submarine that was in refit. When replaced by the Chevaline warhead, the sum total of deployed RVs and warheads was reduced to three boatloads.


title: UGM-27 Polaris

text: The original U.S. Navy Polaris had not been designed to penetrate anti-ballistic missile (ABM) defenses, but the Royal Navy had to ensure that its small Polaris force operating alone, and often with only one submarine on deterrent patrol, could penetrate the ABM screen around Moscow. Britain's submarines featured the Polaris A3T missiles, a modification to the model of the Polaris used by the U.S. from 1968 to 1972. Similar concerns were present in the U.S. as well, resulting in a new American defense program.


title: UGM-27 Polaris

text: The program became known as Antelope, and its purpose was to alter the Polaris. Various aspects of the Polaris, such as increasing deployment efficiency and creating ways to improve the penetrative power were specific items considered in the tests conducted during the Antelope program. The British's uncertainty with their missiles led to the examination of the Antelope program. The assessments of Antelope occurred at Aldermaston. Evidence from the evaluation of Antelope led to the British decision to undertake their program following that of the United States.


title: UGM-27 Polaris

text: The result was a programme called "Chevaline" that added multiple decoys, chaff, and other defensive countermeasures. Its existence was only revealed in 1980, partly because of the cost overruns of the project, which had almost quadrupled the original estimate given when the project was finally approved in January 1975. The program also ran into trouble when dealing with the British Labour Party. Their Chief Scientific Adviser, Solly Zuckerman, believed that Britain no longer needed new designs for nuclear weapons and no more nuclear warhead tests would be necessary. Though the Labour party provided a clear platform on nuclear weapons, the Chevaline program found supporters. One such individual who supported modification to the Polaris was the Secretary of state for Defense, Denis Healey.


title: UGM-27 Polaris

text: Despite the approval of the program, the expenses caused hurdles that augmented the time it took for the system to come to fruition. The cost of the project led to Britain's revisit of disbanding the program in 1977. The system became operational in mid-1982 on , and the last British SSBN submarine was equipped with it in mid-1987. Chevaline was withdrawn from service in 1996.


title: UGM-27 Polaris

text: Though Britain adopted the Antelope program methods, no input on the design came from the United States. Aldermaston was solely responsible for the Chevaline warheads.


title: UGM-27 Polaris

text: The British did not ask to extend the Polaris Sales Agreement to cover the Polaris successor Poseidon due to its cost. The Ministry of Defence upgraded its nuclear missiles to the longer-ranged Trident after much political wrangling within the Callaghan Labour Party government over its cost and whether it was necessary. The outgoing Prime Minister James Callaghan made his government's papers on Trident available to Margaret Thatcher's new incoming Conservative Party government, which took the decision to acquire the Trident C4 missile.


title: UGM-27 Polaris

text: A subsequent decision to upgrade the missile purchase to the even larger, longer-ranged Trident D5 missile was possibly taken to ensure that there was missile commonality between the U.S. Navy and the Royal Navy, which was considerably important when the Royal Navy Trident submarines were also to use the Naval Submarine Base Kings Bay.


title: UGM-27 Polaris

text: Even though the U.S. Navy initially deployed the Trident C4 missile in the original set of its "Ohio"-class submarines, it was always planned to upgrade all of these submarines to the larger and longer-ranged Trident D5 missile—and that eventually, all of the C4 missiles would be eliminated from the U.S. Navy. This change-over has been completely carried out, and no Trident C4 missiles remain in service.


title: UGM-27 Polaris

text: The Polaris missile remained in Royal Navy service long after it had been completely retired and scrapped by the U.S. Navy in 1980–1981. Consequently, many spare parts and repair facilities for the Polaris that were located in the U.S. ceased to be available (such as at Lockheed, which had moved on first to the Poseidon and then to the Trident missile).


title: UGM-27 Polaris

text: During its reconstruction program in 1957–1961, the was fitted with four Polaris missile launchers located in the aft part of the ship. The Italian usage of Polaris missiles was partially the result of the Kennedy administration. Prior to 1961, Italy and Turkey were equipped with Jupiter missiles. Three factors were instrumental in the movement away from the Jupiter project in Italy and Turkey: the president's view of the project, new understanding about weapons systems and the diminished necessity of the Jupiter missile. The Joint Congressional Committee report on Atomic Energy accentuated the three previous factors in Italy's decision to switch to the Polaris missiles.Successful tests held in 1961–1962 induced the United States to study a NATO Multilateral Nuclear Force (MLF), consisting of 25 international surface vessels from the US, United Kingdom, France, Italy, and West Germany, equipped with 200 Polaris nuclear missiles, enabling European allies to participate in the management of the NATO nuclear deterrent.


title: UGM-27 Polaris

text: The report advocated a change from the outdated Jupiter missiles, already housed by the Italians, to the newer missile, Polaris. The report resulted in Secretary of State Dean Rusk and Assistant Secretary of Defense Paul Nitze discussing the possibility of changing the warheads in the Mediterranean. The Italians were not swayed by the American's interest in modernizing their warheads. However, after the Cuban Missile Crisis, Kennedy met the Italian leader Amintore Fanfani in Washington. Fanfani conceded and went along with Kennedy's Polaris plan, despite the Italians hoping to stick with the Jupiter missile.


title: UGM-27 Polaris

text: The MLF plan, as well as the Italian Polaris Program, were abandoned, both for political reasons (in consequence of the Cuban Missile Crisis) and the initial operational availability of the first SSBN , which was capable of launching SLBMs while submerged, a solution preferable to surface-launched missiles.


title: UGM-27 Polaris

text: Italy developed a new domestic version of the missile, the SLBM-designated Alfa. That program was cancelled in 1975 after Italy ratified the Nuclear Non-Proliferation Treaty, with the final launch of the third prototype in 1976.


title: UGM-27 Polaris

text: Two Italian Navy cruisers, commissioned in 1963–1964, were "fitted for but not with" two Polaris missile launchers per ship. All four launchers were built but never installed, and were stored at the La Spezia naval facility.


title: UGM-27 Polaris

text: The , launched in 1969, was also "fitted for but not with" four Polaris missile launchers. During refit periods in 1980–1983, these facilities were removed and used for other weapons and systems.


title: Strategy video game

text: Strategy is a major video game genre that emphasizes thinking and planning over direct instant action in order to achieve victory. Although many types of video games can contain strategic elements, as a genre, strategy games are most commonly defined as those with a primary focus on high-level strategy, logistics and resource management. They are also usually divided into two main sub-categories: turn-based and real-time, but there are also many strategy cross/sub-genres that feature additional elements such as tactics, diplomacy, economics and exploration.


title: Strategy video game

text: A player must plan a series of actions against one or more opponents, and the reduction of enemy forces is usually a goal. Victory is achieved through superior planning, and the element of chance takes a smaller role. In most strategy video games, the player is given a godlike view of the game world, and indirectly controls game units under their command. Thus, most strategy games involve elements of warfare to varying degrees, and feature a combination of tactical and strategic considerations. In addition to combat, these games often challenge the player's ability to explore or manage an economy.


title: Strategy video game

text: Even though there are many action games that involve strategic thinking, they are seldom classified as strategy games. A strategy game is typically larger in scope, and their main emphasis is on the player's ability to outthink their opponent. Strategy games rarely involve a physical challenge, and tend to annoy strategically minded players when they do. Compared to other genres such as action or adventure games where one player takes on many enemies, strategy games usually involve some level of symmetry between sides. Each side generally has access to similar resources and actions, with the strengths and weaknesses of each side being generally balanced.


title: Strategy video game

text: Although strategy games involve strategic, tactical, and sometimes logistical challenges, they are distinct from puzzle games. A strategy game calls for planning around a conflict between players, whereas puzzle games call for planning in isolation. Strategy games are also distinct from construction and management simulations, which include economic challenges without any fighting. These games may incorporate some amount of conflict, but are different from strategy games because they do not emphasize the need for direct action upon an opponent. Nevertheless, some authors consider construction and management simulation games, in particular city-building games, as a part of the wider strategy game genre.


title: Strategy video game

text: Although strategy games are similar to role-playing video games in that the player must manage units with a variety of numeric attributes, RPGs tend to be about a smaller number of unique characters, while strategy games focus on larger numbers of fairly similar units.


title: Strategy video game

text: The player commands their forces by selecting a unit, usually by clicking it with the mouse, and issuing an order from a menu. Keyboard shortcuts become important for advanced players, as speed is often an important factor. Units can typically move, attack, stop, hold a position, although other strategy games offer more complex orders. Units may even have specialized abilities, such as the ability to become invisible to other units, usually balanced with abilities that detect otherwise invisible things. Some strategy games even offer special leader units that provide a bonus to other units. Units may also have the ability to sail or fly over otherwise impassable terrain, or provide transport for other units. Non-combat abilities often include the ability to repair or construct other units or buildings.


title: Strategy video game

text: Even in imaginary or fantastic conflicts, strategy games try to reproduce important tactical situations throughout history. Techniques such as flanking, making diversions, or cutting supply lines may become integral parts of managing combat. Terrain becomes an important part of strategy, since units may gain or lose advantages based on the landscape. Some strategy games such as "Civilization III" and "" involve other forms of conflict such as diplomacy and espionage. However, warfare is the most common form of conflict, as game designers have found it difficult to make non-violent forms of conflict as appealing.


title: Strategy video game

text: Strategy games often involve other economic challenges. These can include building construction, population maintenance, and resource management. Strategy games frequently make use of a windowed interface to manage these complex challenges.


title: Strategy video game

text: Most strategy games allow players to accumulate resources which can be converted to units, or converted to buildings such as factories that produce more units. The quantity and types of resources vary from game to game. Some games will emphasize resource acquisition by scattering large quantities throughout the map, while other games will put more emphasis on how resources are managed and applied by balancing the availability of resources between players. To a lesser extent, some strategy games give players a fixed quantity of units at the start of the game.


title: Strategy video game

text: Strategy games often allow the player to spend resources on upgrades or research. Some of these upgrades enhance the player's entire economy. Other upgrades apply to a unit or class of units, and unlock or enhance certain combat abilities. Sometimes enhancements are enabled by building a structure that enables more advanced structures. Games with a large number of upgrades often feature a technology tree, which is a series of advancements that players can research to unlock new units, buildings, and other capabilities. Technology trees are quite large in some games, and 4X strategy games are known for having the largest.


title: Strategy video game

text: A build order is a linear pattern of production, research, and resource management aimed at achieving a specific and specialized goal. They are analogous to chess openings, in that a player will have a specific order of play in mind, however, the amount of the build order, the strategy around which the build order is built or even which build order is then used varies on the skill, ability and other factors such as how aggressive or defensive each player is.


title: Strategy video game

text: Early strategy games featured a top-down perspective, similar in nature to a board game or paper map. Many later games adopted an isometric perspective. Even with the rise of 3D graphics and the potential to manipulate the camera, games usually feature some kind of aerial view. Very rarely do strategy games show the world from the perspective from an avatar on the ground. This is to provide the player with a big-picture view of the game world, and form more effective strategies.


title: Strategy video game

text: Exploration is a key element in most strategy games. The landscape is often shrouded in darkness, and this darkness is lifted as a player's units enters the area. The ability to explore may be inhibited by different kinds of terrain, such as hills, water, or other obstructions. Even after an area is explored, that area may become dim if the player does not patrol it. This design technique is called the fog of war, where the player can see the terrain but not the units within the explored area. This makes it possible for enemies to attack unexpectedly from otherwise explored areas.


title: Strategy video game

text: Strategy video games are categorized based on whether they offer the continuous gameplay of real-time strategy, or the discrete phases of turn-based strategy. These differences in time-keeping lead to several other differences. Typically, turn-based strategy games have stronger artificial intelligence than real-time strategy games, since the turn-based pace allows more time for complex calculations. But a real-time artificial intelligence makes up for this disadvantage with its ability to manage multiple units more quickly than a human. Overall, real-time strategy games are more action-oriented, as opposed to the abstract planning emphasized in turn-based strategy.


title: Strategy video game

text: The relative popularity of real-time strategy has led some critics to conclude that more gamers prefer action-oriented games. Fans of real-time strategy have criticized the wait times associated with turn-based games, and praised the challenge and realism associated with making quick decisions in real-time. In contrast, turn-based strategy fans have criticized real-time strategy games because most units do not behave appropriately without orders, and thus a turn-based pace allows players to input more realistic and detailed plans. Game theorists have noted that strategic thinking does not lend itself well to real-time action, and turn-based strategy purists have criticized real-time strategy games for replacing "true strategy" with gameplay that rewards "rapid mouse-clicking". Overall, reviewers have been able to recognize the advantages associated with both of the main types of strategy games.


title: Strategy video game

text: Most strategy video games involve a mix of both strategy and tactics. "Tactics" usually refer to how troops are utilized in a given battle, whereas "strategy" describes the mix of troops, the location of the battle, and the commander's larger goals or military doctrine. However, there is also a growing subgenre of purely tactical games, which are referred to as real-time tactics, and turn-based tactics. Game reviewers and scholars sometimes debate whether they are using terminology such as "tactics" or "strategy" appropriately. Chris Taylor, the designer of "Total Annihilation" and "Supreme Commander", has gone so far as to suggest that real-time strategy titles are more about tactics than strategy. But releases that are considered pure tactical games usually provide players with a fixed set of units, and downplay other strategic considerations such as manufacturing, and resource management. Tactical games are strictly about combat, and typically focus on individual battles, or other small sections in a larger conflict.


title: Strategy video game

text: Strategy games can take place in a number of settings. Depending on the theatre of warfare, releases may be noted as naval strategy games, or space strategy games. A title may be noted for its grand strategic scale, whether the game is real-time, or turn-based. Strategy games also draw on a number of historical periods, including World War II, the medieval era, or the Napoleonic era. Some examples of these are: Hearts of Iron IV, Europa Universalis IV, and Victoria II. Some strategy games are even based in an alternate history, by manipulating and rewriting certain historical facts. It is also common to see games based in science fiction or futuristic settings, as well as fantasy settings.


title: Strategy video game

text: Some strategy games are abstract, and do not try to represent a world with high fidelity. Although many of these may still involve combat in the sense that units can capture or destroy each other, these games sometimes offer non-combat challenges such as arranging units in specific patterns. However, the vast majority of computerized strategy games are representational, with more complex game mechanics.


title: Strategy video game

text: Strategy games include single-player gameplay, multiplayer gameplay, or both. Single player games will sometimes feature a campaign mode, which involves a series of matches against several artificial intelligence opponents. Finishing each match or mission will advance the game's plot, often with cut scenes, and some games will reward a completed mission with new abilities or upgrades. Hardcore strategy gamers tend to prefer multiplayer competition, where human opponents provide more challenging competition than the artificial intelligence. Artificial intelligence opponents often need hidden information or bonuses to provide a challenge to players.


title: Strategy video game

text: More recently, massively multiplayer online strategy games have appeared such as "Shattered Galaxy" from 2001. However, these games are relatively difficult to design and implement compared to other massively multiplayer online games, as the numerous player-controlled units create a larger volume of online data. By 2006, reviewers expressed disappointment with the titles produced thus far. Critics argued that strategy games are not conducive to massively multiplayer gameplay. A single victory cannot have much impact in a large persistent world, and this makes it hard for a player to care about a small victory, especially if they are fighting for a faction that is losing an overall war. However, more recent developers have tried to learn from past mistakes, resulting in "Dreamlords" from 2007, and "Saga" from 2008. In 2012, Supercell released Clash of Clans, a mobile strategy video game.


title: Strategy video game

text: The origin of strategy video games is rooted in traditional tabletop strategy games like Chess and Go, as well as board and miniature wargaming. "The Sumerian Game", an early mainframe game written by Mabel Addis, based on the ancient Sumerian city-state of Lagash, was an economic simulation strategy game.


title: Strategy video game

text: The first console strategy game was a "Risk"-like game called "Invasion," released in 1972 for the Magnavox Odyssey. Strategic Simulations (SSI)'s "Computer Bismarck", released in 1980, was the first historical computer wargame. Companies such as SSI, Avalon Hill, MicroProse, and Strategic Studies Group released many strategy titles throughout the 1980s. "Reach for the Stars" from 1983 was one of the first 4X strategy games, which expanded upon the relationship between economic growth, technological progress, and conquest. That same year, "Nobunaga's Ambition" was a conquest-oriented grand strategy wargame with historical simulation elements. "The Lords of Midnight" combined elements of adventure, strategy and wargames, and won the Crash magazine award for Best Adventure game of 1984, as well as Best Strategy Game of the Year at the Golden Joystick Awards


title: Strategy video game

text: 1989's "Herzog Zwei" is often considered the first real-time strategy game, although real-time strategy elements can be found in several earlier games, such as Dan Bunten's "Cytron Masters" and Don Daglow's "Utopia" in 1982; Kōji Sumii's "Bokosuka Wars" in 1983; D. H. Lawson and John Gibson's "Stonkers" and Steven Faber's "Epidemic!" in 1983; and Evryware's "The Ancient Art of War" in 1984.


title: Strategy video game

text: The genre was popularized by "Dune II" three years later in 1992. Brett Sperry, the creator of "Dune II", coined the name "real-time strategy" to help market the new game genre he helped popularize. Real-time strategy games changed the strategy genre by emphasizing the importance of time management, with less time to plan. Real-time strategy games eventually began to outsell turn-based strategy games. With more than 11 million copies sold worldwide by February 2009, "StarCraft" (1998) became one of the best-selling games for the personal computer. It has been praised for pioneering the use of unique "factions" in RTS gameplay, and for having a compelling story.


title: Strategy video game

text: 2002's "" has been an influence on real-time strategy games, especially the addition of role-playing elements and heroes as units. More than the game itself, mods created with the "World Editor" led to lasting changes and inspired many future strategy games. "Defense of the Ancients (DotA)," a community-created mod based on "Warcraft III," is largely attributed as being the most significant inspiration for the multiplayer online battle arena (MOBA) format. Since the format was tied to the "Warcraft" property, developers began to work on their own ""DOTA"-style" games, including "Heroes of Newerth" (2009), "League of Legends" (2010), and the mod's standalone sequel, "Dota 2" (2013). Blizzard Entertainment, the owner of "Warcraft" property, developed a game inspired by "DotA" titled "Heroes of the Storm" (2015), which features an array of heroes from Blizzard's franchises, including numerous heroes from "Warcraft III." Former game journalist Luke Smith called "DotA" "the ultimate RTS".


title: Strategy video game

text: Since its was released in 2000, the "Total War" series by the "Creative Assembly" has sold over 20 million copies, becoming one of the most successful series of strategy games of all time.


title: Strategy video game

text: 4X games are a genre of strategy video game in which players control an empire and "e"x"plore, e"x"pand, e"x"ploit, and e"x"terminate". The term was first coined by Alan Emrich in his September 1993 preview of "Master of Orion" for "Computer Gaming World". Since then, others have adopted the term to describe games of similar scope and design.


title: Strategy video game

text: 4X games are noted for their deep, complex gameplay. Emphasis is placed upon economic and technological development, as well as a range of non-military routes to supremacy. Many 4X games also fit into the category of grand strategy. Games can take a long time to complete since the amount of micromanagement needed to sustain an empire scales as the empire grows. 4X games are sometimes criticized for becoming tedious for these reasons, and several games have attempted to address these concerns by limiting micromanagement.


title: Strategy video game

text: The earliest 4X games borrowed ideas from board games and 1970s text-based computer games. The first 4X games were turn-based, but real-time 4X games are also not uncommon. Many 4X games were published in the mid-1990s, but were later outsold by other types of strategy games. Sid Meier's "Civilization" and the Total War series are important examples from this formative era, and popularized the level of detail that would later become a staple of the genre. In the new 2000 millennium, several 4X releases have become critically and commercially successful.


title: Strategy video game

text: Artillery is the generic name for either early two- or three-player (usually turn-based) computer games involving tanks fighting each other in combat or similar derivative games. Artillery games are among the earliest computer games developed; the theme of such games is an extension of the original uses of computer themselves, which were once used to calculate the trajectories of rockets and other related military-based calculations. Artillery games have been typically described as a type of turn-based tactics game, though they have also been described as a type of "shooting game." Examples of this genre are Pocket Tanks, Hogs of War, Scorched 3D and the Worms series.


title: Strategy video game

text: Early precursors to the modern artillery-type games were text-only games that simulated artillery entirely with input data values. A BASIC game known simply as "Artillery" was written by Mike Forman and was published in "Creative Computing" magazine in 1976. This seminal home computer version of the game was revised in 1977 by M. E. Lyon and Brian West and was known as "War 3"; "War 3" was revised further in 1979 and published as "Artillery-3". These early versions of turn-based tank combat games interpreted human-entered data such as the distance between the tanks, the velocity or "power" of the shot fired and the angle of the tanks' turrets.


title: Strategy video game

text: Auto battler, also known as auto chess, is a type of strategy game that features chess-like elements where players place characters on a grid-shaped battlefield during a preparation phase, who then fight the opposing team's characters without any further direct input from the player. It was created and popularized by "Dota Auto Chess" in early 2019, and saw more games in the genre by other studios, such as "Teamfight Tactics", "Dota Underlords", and "Hearthstone Battlegrounds" releasing soon after.


title: Strategy video game

text: Multiplayer online battle arena (MOBA) is a genre of strategy video games in which each player controls a single character with a set of unique abilities that improve over the course of a game and which contribute to the team's overall strategy. Players work together as a team to achieve a victory condition which is to destroy the opposing team's main structure whilst protecting their own. Player characters, typically called "heroes" or "champions", are assisted by computer-controlled units that periodically spawn in groups and march forward along set paths (called "lanes") toward their enemy's base. Defensive structures, which are usually automatic "towers", are in place to prevent this. The first team to destroy the opponents' main structure wins the match. The genre is seen as a fusion of real-time strategy games, role-playing games, and action games, however, players usually do not construct either buildings or units.


title: Strategy video game

text: This type of multiplayer online video games gained popularity in early 2010s, with "Defense of the Ancients" mod for "Warcraft III", "League of Legends", "Dota 2", "Heroes of the Storm", and "Smite" being popular. MOBA games are well-represented in esports as well. In 2018, prize pools reached over US$60 million, 40% of the year's total esports prize pools.


title: Strategy video game

text: Usually applied only to certain computer strategy games, the moniker real-time strategy (RTS) indicates that the action in the game is continuous, and players will have to make their decisions and actions within the backdrop of a constantly changing game state, and computer real-time strategy gameplay is characterised by obtaining resources, building bases, researching technologies and producing units. Very few non-computer strategy games are real-time; one example is Icehouse.


title: Strategy video game

text: Some players dispute the importance of strategy in real-time strategy games, as skill and manual dexterity are often seen as the deciding factor in this genre of game. According to Troy Dunniway, "A player controls hundreds of units, dozens of buildings and many different events that are all happening simultaneously. There is only one player, and he can only pay attention to one thing at a time. Expert players can quickly flip between many different tasks, while casual gamers have more problems with this." Ernest Adams goes so far as to suggest that real-time gameplay interferes with strategy. "Strategic thinking, at least in the arena of gameplay, does not lend itself well to real-time action".


title: Strategy video game

text: Many strategy players claim that many RTS games really should be labeled as "real-time tactical" (RTT) games since the game play revolves entirely around tactics, with little or even no strategy involved. Massively Multiplayer Online Games (MMOG or MMO) in particular have had a difficult time implementing strategy since having strategy implies some mechanism for "winning". MMO games, by their nature, are typically designed to be never-ending. Nevertheless, some games are attempting to "crack the code," so-to-speak, of the true real-time strategy MMOG. One method by which they are doing so is by making defenses stronger than the weapons, thereby slowing down combat considerably and making it possible for players to more carefully consider their actions during a confrontation. Customizable units are another way of adding strategic elements, as long as players are truly able to influence the capabilities of their units. The industry is seeking to present new candidates worthy of being known for "thought strategy" rather than "dexterity strategy".


title: Strategy video game

text: While "Herzog Zwei" is regarded as the first true RTS game, the defining title for the genre was Westwood Studios's "Dune II", which was followed by their seminal "Command & Conquer" games. Cavedog's "Total Annihilation" (1997), Blizzard's "Warcraft" (1994) series, "StarCraft" (1998) series, and Ensemble Studios' "Age of Empires" (1997) series are some of the most popular RTS games.


title: Strategy video game

text: Massively multiplayer online real-time strategy games, also known as MMORTS, combine real-time strategy (RTS) with a persistent world. Players often assume the role of a general, king, or other type of figurehead leading an army into battle while maintaining the resources needed for such warfare. The titles are often based in a sci-fi or fantasy universe and are distinguished from single or small-scale multiplayer RTS games by the number of players and common use of a persistent world, generally hosted by the game's publisher, which continues to evolve even when the player is offline.


title: Strategy video game

text: Real-time tactics (abbreviated RTT and less commonly referred to as fixed-unit real-time strategy) is a subgenre of tactical wargames played in real-time simulating the considerations and circumstances of operational warfare and military tactics. It is also sometimes considered a subgenre of real-time strategy, and thus may in this context exist as an element of gameplay or as a basis for the whole game. It is differentiated from real-time strategy gameplay by the lack of resource micromanagement and base or unit building, as well as the greater importance of individual units and a focus on complex battlefield tactics. Example titles include "", "World In Conflict", the "Close Combat" series, and early tactical role-playing games such as "Bokosuka Wars", and "Silver Ghost."


title: Strategy video game

text: Tower defense games have a very simple layout. Usually, computer-controlled monsters called "creeps" move along a set path, and the player must place, or "build" towers along this path to kill the creeps. In some games, towers are placed along a set path for creeps, while in others towers can interrupt creep movement and change their path. In most tower defense games different towers have different abilities such as poisoning enemies or slowing them down. The player is awarded money for killing creeps, and this money can be used to buy more towers, or buy upgrades for a tower such as increased power or range. A good example of a game of this genre is Clash Royale made by Finnish developers Supercell.


title: Strategy video game

text: The term turn-based strategy (TBS) is usually reserved for certain computer strategy games, to distinguish them from real-time computer strategy games. A player of a turn-based game is allowed a period of analysis before committing to a game action. Examples of this genre are the "Civilization", "Heroes of Might and Magic", "Making History, Advance Wars" and "Master of Orion".


title: Strategy video game

text: TBS games come in two flavors, differentiated by whether players make their plays simultaneously or take turns. The former types of games are called simultaneously executed TBS games, with "Diplomacy" a notable example. The latter games fall into the player-alternated TBS games category, and are subsequently subdivided into (a) ranked, (b) round-robin start, and (c) random, the difference being the order under which players take their turns. With (a), ranked, the players take their turns in the same order every time. With (b), the first player is selected according to a round-robin policy. With (c), random, the first player is, of course, randomly selected.


title: Strategy video game

text: Almost all non-computer strategy games are turn-based; however, the personal computer game market trend has lately inclined more towards real-time games. Some recent games feature a mix of both real-time and turn-based elements thrown together.


title: Strategy video game

text: Turn-based tactics (TBT), or tactical turn-based (TTB), is a genre of strategy video games that through stop-action simulates the considerations and circumstances of operational warfare and military tactics in generally small-scale confrontations as opposed to more strategic considerations of turn-based strategy (TBS) games.


title: Strategy video game

text: Turn-based tactical gameplay is characterized by the expectation of players to complete their tasks using only the combat forces provided to them, and usually by the provision of a realistic (or at least believable) representation of military tactics and operations. Examples of this genre include the "Wars" and "X-COM" series, as well as tactical role-playing games such as the "Jagged Alliance (series)", "Fire Emblem series" and "Final Fantasy Tactics".


title: Strategy video game

text: Wargames are a subgenre of strategy video games that emphasize strategic or tactical warfare on a map, as well as historical (or near-historical) accuracy.


title: Strategy video game

text: The primary gameplay mode in a wargame is usually tactical: fighting battles. Wargames sometimes have a strategic mode where players may plan their battle or choose an area to conquer, but players typically spend much less time in this mode and more time actually fighting. Because it is difficult to provide an intelligent way to delegate tasks to a subordinate, war games typically keep the number of units down to hundreds rather than hundreds of thousands.


title: Strategy video game

text: Examples of wargames include Koei's "Nobunaga's Ambition" and "Romance of the Three Kingdoms" series, Longbow's "Hegemony" series and several titles by Strategic Simulations, Inc. (SSI) and Strategic Studies Group (SSG).


title: Strategy video game

text: Hybrid strategy games can be viewed as distinct from strategy subgenres in the fact they are not so much iterations or combinations of existing subgenres, but instead seek to combine the strategy genre with completely different genres. Efforts to create such strategy game hybrids were most active in the late 1990's to early 2000's, when first-person shooter (FPS) and real-time strategy (RTS) games were both massively popular. Leading to several notable FPS/RTS hybrid games.


title: Balochistan Liberation Army

text: The Balochistan Liberation Army (; abbreviated BLA), also known as the Baloch Liberation Army, is a Baloch ethnonationalist militant organization based in Afghanistan. The BLA's first recorded activity was during the summer of 2000, after it claimed credit for a series of bombing attacks on Pakistani authorities. The BLA is listed as a terrorist organization by Pakistan, the United Kingdom and the United States.


title: Balochistan Liberation Army

text: Since 2004, the BLA has waged a violent armed struggle against Pakistan for what it claims as self-determination for the Baloch people and the separation of Balochistan from Pakistan. It has been involved in terror attacks against non-Baloch minorities in Balochistan. The BLA operates mainly in Balochistan, the largest province of Pakistan, where it carries out attacks against the Pakistan Armed Forces, civilians and foreign nationals. Although the BLA was officially founded in 2000, the media, and some analysts, speculate that the group is a resurgence of prior Baloch ethnonationalism insurgencies and, more specifically, the Independent Balochistan Movement of 1973 to 1977.


title: Balochistan Liberation Army

text: According to some sources, two former KGB agents code named 'Misha' and 'Sasha' were among the architects of the original BLA. According to the two KGB agents, the original BLA was built around the core of the Baloch Student Organization (BSO). The BLA disappeared following the withdrawal of the Soviet Union from Afghanistan as the USSR had been its main source of funding.


title: Balochistan Liberation Army

text: On 10 February 1973, Pakistani police and paramilitary raided the Iraqi embassy in Islamabad without the prior permission of the Iraqi government. During the raid, a large cache of small arms, ammunition, grenades, and other supplies were found in crates marked 'Foreign Ministry, Baghdad'; these were believed to be destined for Baloch rebels. Pakistan responded by expelling and declaring persona non grata the Iraqi Ambassador, Hikmat Sulaiman, and other consular staff. In a letter to President Nixon on 14 February, Bhutto blamed India and Afghanistan, besides Iraq and the Soviet Union, for involvement in a "conspiracy [...] [with] subversive and irredentist elements which seek to disrupt Pakistan's integrity"


title: Balochistan Liberation Army

text: David Wright-Neville wrote that besides Pakistan, some Western observers also believe India secretly funds the BLA. However, in August 2013, US Special Representative James Dobbins said, "The dominant infiltration of militants is from Pakistan into Afghanistan, but we recognize that there is some infiltration of hostile militants from the other direction. So Pakistan's concerns aren't groundless. They are simply, in our judgment, somewhat exaggerated."


title: Balochistan Liberation Army

text: Some have reported that Hyrbyair Marri has been the group's leader since 2007. Still, in an interview in 2015, he denied having any contact with the group. Hyrbyair's brother Balach had led the group from 2000 until he was killed in 2007.


title: Balochistan Liberation Army

text: The Indian newspaper "The Hindu" reported that BLA commanders had previously sought medical treatment in India's hospitals, often in disguise or using fake identities. In one such case, a militant commander in charge of the city of Khuzdar was based in Delhi for at least six months in 2017 where he underwent extensive treatment for kidney-related ailments. Baloch militants' visits to India were often under assumed identities. Another Baloch Liberation Army commander, Aslam Baloch, was also alleged to have visited India. Previously, the "Express Tribune" had reported that Aslam Baloch was undergoing treatment at a hospital in New Delhi.


title: Balochistan Liberation Army

text: Pakistan has often accused the BLA of being an Indian proxy, alleging that Indian consulates in Kandahar and Jalalabad, Afghanistan, were providing arms, training, and financial aid to the BLA in an attempt to destabilize Pakistan. Baloch separatist Hyrbyair Marri denies the group has links with India. However, he has also claimed that he is not a BLA member. India has also denied helping the BLA.


title: Balochistan Liberation Army

text: Afghanistan has acknowledged that they have been providing covert support to the Baloch Liberation Army. After the death of Aslam Baloch, alias Achu, in Kandahar, Afghan officials stated that the Afghan police chief Abdul Raziq Achakzai had housed Aslam Baloch and other separatists in Kandahar for years. Afghan news channel Tolonews reported that Aslam Baloch has been residing in Afghanistan since 2005.


title: Balochistan Liberation Army

text: Pakistan designated the Balochistan Liberation Army as a terrorist organisation on 7 April 2006 after the group conducted a series of attacks targeting security personnel. On 17 July 2006, the British government followed suit, listing the BLA as a "proscribed group" based on the Terrorism Act 2000. However, the U.K. has harboured Hyrbyair Marri, leader of the BLA, as a refugee, in spite of protest by Pakistan. The group's actions have been described as terrorism by the United States Department of State.


title: Balochistan Liberation Army

text: The United States designated the group as a global terrorist organization on 2 July 2019. The United States also froze assets belonging to the BLA. The European Union has also designated the Balochistan Liberation Army (BLA) as a terrorist organization. After BLA attacks on Chinese citizens, Chinese officials called on the Pakistani government to carry out additional strikes against the group.


title: Balochistan Liberation Army

text: On 15 April 2009, Baloch activist Brahamdagh Khan Bugti—who has been accused by the Pakistani government of being a leader of the BLA—called for Balochis to kill non-Balochis residing in Balochistan, including civilians. Targeted attacks against Punjabi residents began soon after, with the BLA estimating 500 deaths. BLA leaders later claimed responsibility for inciting the attacks. Since the start of the insurgency, the BLA has targeted people from various ethnic backgrounds like Pashtuns, Sindhis, and Punjabis, whom the BLA considered outsiders in the province.


title: Comprehensive school

text: A comprehensive school typically describes a secondary school for pupils aged approximately 11–18, that does not select its intake on the basis of academic achievement or aptitude, in contrast to a selective school system where admission is restricted on the basis of selection criteria, usually academic performance. The term is commonly used in relation to England and Wales, where comprehensive schools were introduced as state schools on an experimental basis in the 1940s and became more widespread from 1965. They may be part of a local education authority or be a self governing academy or part of a multi-academy trust.


title: Comprehensive school

text: About 90% of English secondary school pupils attend a comprehensive school (academy schools, community schools, faith schools, foundation schools, free schools, studio schools, university technical colleges, state boarding schools, City Technology Colleges, etc). Specialist schools may also select up to 10% of their intake for aptitude in their specialism. A school may have a few specialisms, like arts (media, performing arts, visual arts), business and enterprise, engineering, humanities, languages, mathematics, computing, music, science, sports, and technology. They are not permitted to select on academic ability generally.


title: Comprehensive school

text: There were over 24,323 schools in England in 2018. There were 391 nurseries, 16,769 primary schools, 3,448 secondary schools, 2,319 independent schools, 1,044 special schools and 352 pupil referral units (PRUs). In Wales there were 1,569 schools. There were 9 nursery schools, 1,238 primary schools, 19 middle schools, 187 secondary schools, 75 independent schools and 41 special schools. Comprehensive schools correspond broadly to the public school in the United States, Canada and Australia.


title: Comprehensive school

text: Comprehensive schools provide an entitlement curriculum to all children, without selection whether due to financial considerations or attainment. A consequence of that is a wider ranging curriculum, including practical subjects such as design and technology and vocational learning, which were less common or non-existent in grammar schools. Providing post-16 education cost-effectively becomes more challenging for smaller comprehensive schools, because of the number of courses needed to cover a broader curriculum with comparatively fewer students. This is why schools have tended to get larger and also why many local authorities have organised secondary education into 11–16 schools, with the post-16 provision provided by sixth form colleges and further education colleges. Comprehensive schools do not select their intake on the basis of academic achievement or aptitude. In addition, government initiatives such as the City Technology Colleges and specialist schools programmes have expanded the comprehensive model. City Technology Colleges are independent schools in urban areas that are free to go to. They’re funded by central government with company contributions and emphasise teaching science and technology.


title: Comprehensive school

text: English secondary schools are mostly comprehensive (i.e. no entry exam), although the intake of comprehensive schools can vary widely, especially in urban areas with several local schools. Nearly 90% of state-funded secondary schools are specialist schools, receiving extra funding to develop one or more subjects (performing arts, business, humanities, art and design, languages, science, mathematics, technology, engineering, sports, etc) in which the school specialises, which can select up to 10% of their intake for aptitude in the specialism. In these schools children could be selected on the basis of curriculum aptitude related to the school's specialism even though the schools do take quotas from each quartile of the attainment range to ensure they were not selective by attainment. In the selective school system, which survives in several parts of the United Kingdom, admission is dependent on selection criteria, most commonly a cognitive test or tests. Most comprehensives are secondary schools for children between the ages of 11 to 16, but in a few areas there are comprehensive middle schools, and in some places the secondary level is divided into two, for students aged 11 to 14 and those aged 14 to 18, roughly corresponding to the US middle school (or junior high school) and high school, respectively. With the advent of Key Stages in the National Curriculum some local authorities reverted from the Middle School system to 11–16 and 11–18 schools so that the transition between schools corresponds to the end of one key stage and the start of another. In principle, comprehensive schools were conceived as "neighbourhood" schools for all students in a specified catchment area.


title: Comprehensive school

text: Maths free schools like Exeter Mathematics School are for 16 to 19 year pupils who have a great aptitude for maths. As set out in the government’s Industrial Strategy, maths schools help to encourage highly skilled graduates in sectors that depend on science, technology, engineering and maths (STEM) skills. The aim of maths schools is to prepare the most mathematically able pupils to succeed in mathematics-related disciplines at highly selective maths universities and pursue mathematically intensive careers. Maths schools can also be centres of excellence in raising attainment, supporting and influencing the teaching of mathematics in their surrounding area, and are central to their associated universities’ widening participation commitments.


title: Comprehensive school

text: Technical and vocational education in somprehensive schools are introduced during the secondary school years and goes on until further and higher education. Secondary vocational education is also known as further education. Further education incorporates vocational oriented education as well as a combination of general secondary education. Students can also go on to a further education college to prepare themselves for the Business and Technology Education Council (BTEC), T-levels, and National Vocational Qualifications (NVQs). Major provider of vocational qualifications in England include the City and Guilds of London Institute and Edexcel. Higher National Certificates and Higher National Diplomas typically require 1 and 2 years of full-time study and credit from either HNE or Diplomas can be transferred toward an undergraduate degree. Along with the HNC and HND, students who are interested in other vocational qualifications may pursue a foundation degree, which is a qualification that trains people to be highly skilled technicians. The National Apprenticeship Service also offers vocational education where people at ages of 16 and older enter apprenticeships in order to learn a skilled trade. There are over 60 different certifications can be obtained through an apprenticeship, which typically lasts from up to 3 years. Trades apprentices receive paid wages during training and spend one day at school and the rest in the workplace to hone their skills.The first comprehensives were set up after the Second World War. In 1946, for example, Walworth School was one of five 'experimental' comprehensive schools set up by the London County Council Another early comprehensive school was Holyhead County School in Anglesey in 1949. Coventry opened two Comprehensive Schools in 1954 by combining Grammar Schools and Secondary Modern Schools. These were Caludon Castle and Woodlands. Another early example was Tividale Comprehensive School in Tipton. The first, purpose-built comprehensive in the North of England was Colne Valley High School near Huddersfield in 1956.


title: Comprehensive school

text: The largest expansion of comprehensive schools resulted from a policy decision taken in 1965 by Anthony Crosland, Secretary of State for Education in the 1964–1970 Labour government. The policy decision was implemented by Circular 10/65, a request to local education authorities to plan for conversion. Students sat the 11+ examination in their last year of primary education and were sent to one of a secondary modern, secondary technical or grammar school depending on their perceived ability. Secondary technical schools were never widely implemented and for 20 years there was a virtual bipartite system which saw fierce competition for the available grammar school places, which varied between 15% and 25% of total secondary places.


title: Comprehensive school

text: In 1970 Margaret Thatcher, the Secretary of State for Education in the new Conservative government, ended the compulsion on local authorities to convert, however, many local authorities were so far down the path that it would have been prohibitively expensive to attempt to reverse the process, and more comprehensive schools were established under Thatcher than any other education secretary. By 1975 the majority of local authorities in England and Wales had abandoned the 11-Plus examination and moved to a comprehensive system. Over that 10-year period many secondary modern schools and grammar schools were amalgamated to form large neighbourhood comprehensives, whilst a number of new schools were built to accommodate a growing school population. By the mid-1970s the system had been almost fully implemented, with virtually no secondary modern schools remaining. Many grammar schools were either closed or changed to comprehensive status. Some local authorities, including Sandwell and Dudley in the West Midlands, changed all of its state secondary schools to comprehensive schools during the 1970s.


title: Comprehensive school

text: In 1976 the future Labour Prime Minister James Callaghan launched what became known as the 'great debate' on the education system. He went on to list the areas he felt needed closest scrutiny: the case for a core curriculum, the validity and use of informal teaching methods, the role of school inspection and the future of the examination system. Comprehensive school remains the most common type of state secondary school in England, and the only type in Wales. They account for around 90% of pupils, or 64% if one does not count schools with low-level selection. This figure varies by region.


title: Comprehensive school

text: Since the 1988 Education Reform Act, parents have a right to choose which school their child should go to or whether to not send them to school at all and to home educate them instead. The concept of "school choice" introduces the idea of competition between state schools, a fundamental change to the original "neighbourhood comprehensive" model, and is partly intended as a means by which schools that are perceived to be inferior are forced either to improve or, if hardly anyone wants to go there, to close down. Government policy is currently promoting 'specialisation' whereby parents choose a secondary school appropriate for their child's interests and skills. Most initiatives focus on parental choice and information, implementing a pseudo-market incentive to encourage better schools. Both Conservative Party and Labour governments experimented with alternatives to the original neighbourhood comprehensive.


title: Comprehensive school

text: Following the advice of Sir Cyril Taylor—former businessman and Conservative politician, and chairman of the Specialist Schools and Academies Trust (SSAT)—in the mid-1990s, all parties have backed the creation of specialist schools, which focus on excellence in a particular subject and are theoretically allowed to select up to 10% of their intake. This policy consensus had brought to an end the notion that all children will go to their local school, and assumes parents will choose a school they feel most meets their child's needs.


title: Comprehensive school

text: All maintained schools in England are required to follow the National Curriculum, which is made up of twelve subjects. Every state school must offer a curriculum which is balanced and broadly based and which promotes the spiritual, moral, cultural, mental and physical development of pupils at the school and of society, and prepares pupils at the school for the opportunities, responsibilities and experiences of later life. For each of the statutory curriculum subjects, the Secretary of State for Education is required to set out a Programme of Study which outlines the content and matters which must be taught in those subjects at the relevant Key Stages. Teachers should set high expectations for every pupil. They should plan stretching work for pupils whose attainment is significantly above the expected standard. Teachers should use appropriate assessment to set targets which are deliberately ambitious.


title: Comprehensive school

text: Under the National Curriculum, all pupils undergo National Curriculum assessments at the end of Key Stage 2 in Year 6 in the core subjects of English, Mathematics and Science. Individual teacher assessment is used for foundation subjects, such as art and design, geography, history, design and technology, and computing. Pupils take GCSE exams at Key Stage 4 in Year 11, but may also choose to work towards the attainment of alternative qualifications, such as the NVQs and Business and Technology Education Council. Pupils take GCSEs examinations in the core English literature, English language, mathematics, science, and entitlement subjects from the arts, humanities, design and technology, and languages. The core subjects English, Mathematics and Science are compulsory for all pupils aged 5 to 16. A range of other subjects, known as foundation subjects, are compulsory in each Key Stage:


title: Comprehensive school

text: In addition to the compulsory subjects, pupils at Key Stage 4 have a statutory entitlement to be able to study at least one subject from the arts (comprising art and design, music, photography, dance, drama and media arts), design and technology (comprising design and technology, electronics, engineering, food preparation and nutrition), the humanities (comprising geography and history), and modern foreign languages. Optional subjects include computer science, business studies, economics, astronomy, classical civilisation, film studies, geology, psychology, sociology, ancient languages, and ancient history.


title: Comprehensive school

text: The Department for Education has drawn up a list of preferred subjects known as the English Baccalaureate on the results in eight GCSEs including English, mathematics, the sciences (physics, chemistry, biology, computer science), history, geography, and an ancient or modern foreign language.


title: Comprehensive school

text: All schools are required to make provision for a daily act of collective worship and must teach religious education to pupils at every key stage and sex and relationships education to pupils in secondary education. Parents can withdraw their children for all or part of the lessons. Local councils are responsible for deciding the RE syllabus, but faith schools and academies can set their own. All schools should make provision for personal, social, health and economic education (PSHE). Schools are also free to include other subjects or topics of their choice in planning and designing their own programme of education.


title: Comprehensive school

text: Children are normally placed in year groups determined by the age they will attain at their birthday during the school year. In most cases progression from one year group to another is based purely on chronological age, although it is possible in some circumstances for a student to repeat or skip a year. Repetition may be due to a lack of attendance, for example from a long illness, and especially in Years requiring standard tests. A child significantly more advanced than their classmates may be forwarded one or more years.


title: Comprehensive school

text: State-funded nursery education is available from the age of 3, and may be full-time or part-time, though this is not compulsory. If registered with a state school, attendance is compulsory beginning with the term following the child's fifth birthday. Children can be enrolled in the reception year in September of that school year, thus beginning school at age 4 or 4.5. Unless the student chooses to stay within the education system, compulsory school attendance ends on the last Friday in June during the academic year in which a student attains the age of 16.


title: Comprehensive school

text: In the vast majority of cases, pupils progress from primary to secondary levels at age 11; in some areas either or both of the primary and secondary levels are further subdivided. A few areas have three-tier education systems with an intermediate middle level from age 9 to 13. Years 12 and 13 are often referred to as "lower sixth form" and "upper sixth form" respectively, reflecting their distinct, voluntary nature as the A-level years. While most secondary schools enter their pupils for A-levels, some schools offer the International Baccalaureate or Cambridge Pre-U qualifications instead.


title: Comprehensive school

text: Scotland has a very different educational system from England and Wales, though also based on comprehensive education. It has different ages of transfer, different examinations and a different philosophy of choice and provision. All publicly funded primary and secondary schools are comprehensive. The Scottish Government has rejected plans for specialist schools as of 2005.


title: Comprehensive school

text: When the first comprehensive schools appeared in the 1950s, the Australian Government started to transition to comprehensive schooling which has been expanding and improving ever since. Prior to the transition into comprehensive schooling systems, primary and secondary state schools regularly measured students' academic merit based on their performance in public examinations. The state of Western Australia was the first to replace many multilateral school systems, proceeding with Queensland, and finally South Australia and Victoria.


title: Comprehensive school

text: The Australian education system is organised through three compulsory school types. Students commence their education in Primary school, which runs for seven or eight years, starting at kindergarten through to Year 6 or 7. The next is Secondary school which runs for three or four years, from Year 7 or 8 to Year 10. Finally, Senior Secondary school which runs for two years, completing Years 11 and 12. Each school tier follows a comprehensive curriculum that is categorised into sequences for each Year-level. The Year-level follows specific sequence content and achievement for each subject, which can be interrelated through cross-curricula. In order for students to complete and graduate each tier-level of schooling, they need to complete the subject sequences of content and achievement. Once students have completed Year 12, they may choose to enter into Tertiary education. The two-tier Tertiary education system in Australia includes both higher education (i.e.: University, College, other Institutions) and vocational education and training (VET). Higher education works off of the Australian Qualifications Framework and prepares Australians for an academic route that may take them into the theoretical and philosophical lenses of their career options.


title: Technical death metal

text: Technical death metal (also referred to as tech-death) is a musical subgenre of death metal that began and developed in the early- to mid-1990s, with particular focus on challenging, demanding instrumental skill and complex songwriting.


title: Technical death metal

text: Technical experimentation in death metal began in the late 1980s and early 1990s by four bands that are often grouped together as "technical death metal's Big Four" – Death, Pestilence, Atheist, and Cynic – as well as Nocturnus; all but Pestilence being part of the Florida death metal scene.


title: Technical death metal

text: Some of the distinct features of this genre include dynamic song structures, complex and atypical rhythmic structures, abundant use of diminished chords and arpeggios, frequent employment of odd time chord progressions, and constant use of string skipping on the guitars. Bass lines are usually complex, and the drums are extremely fast-paced with abundant use of blast beats and other extreme drumming techniques. The technical death metal genre has also been influenced by mostly jazz fusion, as well as thrash metal and progressive/technical-inspired heavy metal bands like Death, Megadeth, Slayer, Voivod, Kreator, Dark Angel, Coroner, Sadus, and Watchtower, the latter of whose second album "Control and Resistance" (1989) is often considered to be one of the sources of inspiration for the genre.


title: Technical death metal

text: The 1990 album "The Key" by Nocturnus has been cited as the first progressive death metal album. One of the key works that cemented the subgenre was Atheist's debut album "Piece of Time", also released in 1990, which took death metal into a more intricate level while incorporating influences ranging from jazz fusion to progressive metal. In 1991, New York death metal group Suffocation released their debut album "Effigy of the Forgotten", which focused on pairing speed and brutality with a "sophisticated" sense of songwriting. Atheist's second album "Unquestionable Presence", Pestilence's third album "Testimony of the Ancients", and Death's fourth album "Human" were all released the same year, defining the path for death metal's newly found intricateness and having proved to be especially influential on later 1990s and 2000s technical death metal bands.


YU-NO: A Girl Who Chants Love at the Bound of this World is a visual novel adventure game developed and published by ELF Corporation. It was originally released in 1996 as an eroge for the NEC PC-98 Japanese home computer and later ported to the Sega Saturn and Microsoft Windows platforms without the sexual content. The story follows the protagonist travelling between parallel worlds to solve the mystery of his parents' disappearance. The game uses concepts from science fiction, physics, mathematics, philosophy, history and religion to construct a unique fictional universe. The "Auto Diverge Mapping System" (A.D.M.S.) that displays the branching parallel worlds and storylines as a tree helps the player navigate the game world.


title: YU-NO: A Girl Who Chants Love at the Bound of this World

text: "YU-NO" was written and produced by Hiroyuki Kanno, and its FM-synth music soundtrack was composed by Ryu Umemoto, Ryu Takami and Kazuhiro Kanae, who had previously worked on C's Ware titles such as "Eve Burst Error" (1995). "YU-NO" was well-received and influential in Japan, where it revolutionized the visual novel industry and in turn had an impact on the manga and anime industries, inspiring numerous visual novel, manga and anime works.


text: In 2017, 5pb. (Later Mages) developed and published a remake of the game for the PlayStation Vita and PlayStation 4. Spike Chunsoft released this version for PlayStation 4, Microsoft Windows, and Nintendo Switch in 2019. The game has also been adapted into a four-part hentai original video animation, a manga and novels, and a TV anime series by Feel that aired from April to October 2019. The TV anime series is licensed by Funimation and Crunchyroll outside Japan.


text: referred to in the title is the location the protagonist reaches at the conclusion of the game. Yu-no is the name of a girl central to the story. The creators said "YU-NO", which comes last word in the Japanese title, is meant to be a subtitle. The English version of the title that is used in some artwork is stylized as "YU-NO: A girl who chants love at the bound of this world.", with a period. A connection to Harlan Ellison's short story "The Beast that Shouted Love at the Heart of the World" has been noted by Robert Allen of "Tech-Gaming".


text: The PC-98 and Sega Saturn versions of the game are slightly different. Unless otherwise noted, the following information describes the PC-98 version.


text: Players travel between parallel worlds using a reflector device that uses stones to mark positions as returning locations so they can retrace their steps and enter an alternative universe. The game implements an original system called Automatic Diverge Mapping System (A.D.M.S.) that at any time in the game displays a screen showing the direction in which the player was heading along the branching plot lines. Similar systems have later been used in the 2010 role-playing video game "Radiant Historia" and the PSP version of "".


text: When a branch in the storyline nears, an indicator on the game's reflector device blinks. When the players' choice advances the storyline, their routes are recorded in the "divergence map" and the device plays a sound. The player is tasked with collecting eight jewels that are the power source of the reflector device; the divergence map shows the locations of all jewels within the storylines even before the player has reached them. In this way, A.D.M.S. is used to search through the parallel worlds. The divergence map displays time from left to right and concurrent parallel worlds are shown vertically.