Open world
In video games, an open world is a game mechanic of using a virtual world that the player can explore and approach objectives freely, as opposed to a world with more linear and structured gameplay. While games have used open-world designs since the 1980s, the implementation in "Grand Theft Auto III" (2001) set a standard for the concept which has been used since. Games with open or free-roaming worlds typically lack level structures like walls and locked doors, or the invisible walls in more open areas that prevent the player from venturing beyond them; only at  the bounds of an open-world game will players be limited by geographic features like vast oceans or impassable mountains. Players typically do not encounter loading screens common in linear level designs when moving about the game world, with the open-world game using strategic storage and memory techniques to load the game world in a dynamic and seamless manner. Open-world games still enforce many restrictions in the game environment, either because of absolute technical limitations or in-game limitations imposed by a game's linearity. While the openness of the game world is an important facet to games  featuring open worlds, the main draw of open-world games is about providing the player with autonomy – not so much the freedom to do anything they want in the game (which is nearly impossible with current computing technology), but the ability to choose how to approach the game and its challenges in the order and manner as the player desires while still constrained by gameplay rules. Examples of high level of autonomy in computer games can be found in massively multiplayer online role-playing games (MMORPG) or in single-player games adhering to the open-world concept such as the  Fallout series. The main appeal of open-world gameplay is that it provides a simulated reality and allows players to develop their character and its behavior in the direction and pace of their own choosing. In these cases, there is often no concrete goal or end to the game, although there may be the main storyline, such as with games like "". Gameplay and design. An open world is a level or game designed as nonlinear, open areas with many ways to reach an objective. Some games are designed with both traditional and open-world levels. An open world facilitates greater  exploration than a series of smaller levels, or a level with more linear challenges. Reviewers have judged the quality of an open world based on whether there are interesting ways for the player to interact with the broader level when they ignore their main objective. Some games actually use real settings to model an open world, such as New York City. A major design challenge is to balance the freedom of an open world with the structure of a dramatic storyline. Since players may perform actions that the game designer did not expect, the game's writers must find creative  ways to impose a storyline on the player without interfering with their freedom. As such, games with open worlds will sometimes break the game's story into a series of missions, or have a much simpler storyline altogether. Other games instead offer side-missions to the player that do not disrupt the main storyline. Most open-world games make the character a blank slate that players can project their own thoughts onto, although several games such as "" offer more character development and dialogue. Writing in 2005, David Braben described the narrative structure of current video games as "little different to  the stories of those Harold Lloyd films of the 1920s", and considered genuinely open-ended stories to be the "Holy Grail we are looking for in fifth generation gaming". Gameplay designer Manveer Heir, who worked on "Mass Effect 3" and "Mass Effect Andromeda" for Electronic Arts, said that there are difficulties in the design of an open-world game since it is difficult to predict how players will approach solving gameplay challenges offered by a design, in contrast to a linear progression, and needs to be a factor in the game's development from its onset. Heir opined that some  of the critical failings of "Andromeda" were due to the open world being added late in development. Some open-world games, to guide the player towards major story events, do not provide the world's entire map at the start of the game, but require the player to complete a task to obtain part of that map, often identifying missions and points of interest when they view the map. This has been derogatorily referred to as "Ubisoft towers", as this mechanic was promoted in Ubisoft's "Assassin's Creed" series (the player climbing a large tower as to observe the  landscape around it and identify waypoints nearby) and reused in other Ubisoft games, including "Far Cry", "" and "Watch Dogs". Other games that use this approach include "" and "". Rockstar games like "GTA IV" and the "Red Dead Redemption" series lock out sections of the map as "barricaded by law enforcement" until a specific point in the story has been reached. Games with open worlds typically give players infinite lives or continues, although some force the player to start from the beginning should they die too many times. There is also a risk that players may get lost as they explore an  open world; thus designers sometimes try to break the open world into manageable sections. The scope of open-world games requires the developer to fully detail every possible section of the world the player may be able to access, unless methods like procedural generation are used. The design process, due to its scale, may leave numerous game world glitches, bugs, incomplete sections, or other irregularities that players may find and potentially take advantage of. The term "open world jank" has been used to apply to games where the incorporation of the open world gameplay elements may be poor, incomplete, or  unnecessary to the game itself such that these glitches and bugs become more apparent, though are generally not game-breaking, such as the case for "No Man's Sky" near its launch. Open world, sandbox games, and emergent gameplay. The mechanics of open-world games are often overlapped with ideas of sandbox games, but these are considered different terms. Whereas open world refers to the lack of limits for the player's exploration of the game's world, sandbox games are based on the ability of giving the player tools for creative freedom within the game to approach objectives, if  such objectives are present. For example, "Microsoft Flight Simulator" is an open-world game as one can fly anywhere within the mapped world, but is not considered a sandbox game as there are few creative aspects brought into the game. The combination of open world and sandbox mechanics can lead towards emergent gameplay, complex reactions that emerge (either expectedly or unexpectedly) from the interaction of relatively simple game mechanics. According to Peter Molyneux, emergent gameplay appears wherever a game has a good simulation system that allows players to play in the world and have it respond realistically to their actions . It is what made "SimCity" and "The Sims" compelling to players. Similarly, being able to freely interact with the city's inhabitants in "Grand Theft Auto" added an extra dimension to the series. In recent years game designers have attempted to encourage emergent play by providing players with tools to expand games through their own actions. Examples include in-game web browsers in "EVE Online" and "The Matrix Online"; XML integration tools and programming languages in "Second Life"; shifting exchange rates in "Entropia Universe"; and the complex object-and-grammar system used to solve puzzles in "Scribblenauts". Other examples of  emergence include interactions between physics and artificial intelligence. One challenge that remains to be solved, however, is how to tell a compelling story using only emergent technology. In an op-ed piece for BBC News, David Braben, co-creator of "Elite", called truly open-ended game design "The Holy Grail" of modern video gaming, citing games like "Elite" and the "Grand Theft Auto" series as early steps in that direction. Peter Molyneux has also stated that he believes emergence (or emergent gameplay) is where video game development is headed in the future. He has attempted to implement open-world gameplay  to a great extent in some of his games, particularly "Black & White" and "Fable". Procedural generation of open worlds. Procedural generation refers to content generated algorithmically rather than manually, and is often used to generate game levels and other content. While procedural generation does not guarantee that a game or sequence of levels is nonlinear, it is an important factor in reducing game development time and opens up avenues making it possible to generate larger and more or less unique seamless game worlds on the fly and using fewer resources. This kind of procedural generation is known as worldbuilding, in  which general rules are used to construct a believable world. Most 4X and roguelike games make use of procedural generation to some extent to generate game levels. SpeedTree is an example of a developer-oriented tool used in the development of "" and aimed at speeding up the level design process. Procedural generation also made it possible for the developers of "Elite", David Braben and Ian Bell, to fit the entire game—including thousands of planets, dozens of trade commodities, multiple ship types and a plausible economic system—into less than 22 kilobytes of memory. More recently, "No Man's Sky  procedurally generated over 18 quintillion planets including flora, fauna, and other features that can be researched and explored. History. 20th century. There is no consensus on what the earliest open-world game is, due to differing definitions of how large or open a world needs to be. Inverse" provides some early examples games that established elements of the open world: "Jet Rocket", a 1970 Sega electro-mechanical arcade game that, while not a video game, predated the flight simulator genre to give the player free roaming capabilities, and "dnd", a 1975 text-based adventure game for the PLATO system that  offered non-linear gameplay. "Ars Technica" traces the concept back to the free-roaming exploration of 1976 text adventure game "Colossal Cave Adventure", which inspired the free-roaming exploration of "Adventure" (1980), but notes that it was not until 1984 that what "we now know as open-world gaming" took on a "definite shape" with 1984 space simulator "Elite", considered a pioneer of the open world; Gamasutra argues that its open-ended sandbox style is rooted in flight simulators, such as SubLOGIC's "Flight Simulator" (1979/1980), noting most flight sims "offer a 'free flight' mode that allows players to simply  pilot the aircraft and explore the virtual world". Others trace the concept back to 1981 CRPG "", which had a free-roaming overworld map inspired by tabletop RPG "Dungeons & Dragons". The overworld maps of the first five "Ultima" games, released up to 1988, lacked a single, unified scale, with towns and other places represented as icons; this style was adopted by the first three "Dragon Quest" games, released from 1986 to 1988 in Japan. Early examples of open-world gameplay in adventure games include "The Portopia Serial Murder Case" (1983) and "The Lords of Midnight" (1984), with open-world elements also  found in "The Hobbit" (1982) and "Valhalla" (1983). The strategy video game, "The Seven Cities of Gold" (1984), is also cited as an early open-world game, influencing "Sid Meier's Pirates!" (1987). Eurogamer also cites British computer games such as "Ant Attack" (1983) and "Sabre Wulf" (1984) as early examples. According to "Game Informer"s Kyle Hilliard, "Hydlide" (1984) and "The Legend of Zelda" (1986) were among the first open-world games, along with "Ultima". IGN traces the roots of open-world game design to "The Legend of Zelda", which it argues is "the first really good game based on  exploration", while noting that it was anticipated by "Hydlide", which it argues is "the first RPG that rewarded exploration". According to GameSpot, never "had a game so open-ended, nonlinear, and liberating been released for the mainstream market" with "The Legend of Zelda". According to "The Escapist", "The Legend of Zelda" was an early example of open-world, nonlinear gameplay, with an expansive and cohesive world, inspiring many games to adopt a similar open-world design. "Mercenary" (1985) has been cited as the first open world 3D action-adventure game. There were also other open-world games in the 1980s , such as "Back to Skool" (1985), "Turbo Esprit" (1986) and "Alternate Reality: The City" (1985). "Wasteland", released in 1988, is also considered an open-world game. The early 1990s saw open-world games such as "The Terminator" (1990), "The Adventures of Robin Hood" (1991), and "Hunter" (1991), which IGN describes as the first sandbox game to feature full 3D, third-person graphics, and Ars Technica argues "has one of the strongest claims to the title of "GTA" forebear". Sierra On-Line's 1992 adventure game "King's Quest VI" has an open world; almost half of the quests are optional , many have multiple solutions, and players can solve most in any order. Atari Jaguar launch title, Cybermorph (1993), was notable for its open 3D polygonal-world and non-linear gameplay. "Quarantine" (1994) is an example of an open-world driving game from this period, while "Iron Soldier" (1994) is an open-world mech game. The director of 1997's "Blade Runner" argues that that game was the first open world three-dimensional action adventure game. IGN considers Nintendo's "Super Mario 64" (1996) revolutionary for its 3D open-ended free-roaming worlds, which had rarely been seen in 3D games  before, along with its analog stick controls and camera control. Other 3D examples include "Mystical Ninja Starring Goemon" (1997), "" (1998), the DMA Design (Rockstar North) game "Body Harvest" (1998), the Angel Studios (Rockstar San Diego) games "Midtown Madness" (1999) and "" (2000), the Reflections Interactive (Ubisoft Reflections) game "Driver" (1999), and the Rareware games "Banjo-Kazooie" (1998), "Donkey Kong 64" (1999), and "Banjo-Tooie" (2000). 1UP considers Sega's adventure "Shenmue" (1999) the originator of the "open city" subgenre, touted as a "FREE" ("Full Reactive Eyes Entertainment") game giving players the freedom to explore an expansive sandbox city with its own  day-night cycles, changing weather, and fully voiced non-player characters going about their daily routines. The game's large interactive environments, wealth of options, level of detail and the scope of its urban sandbox exploration has been compared to later sandbox games like "Grand Theft Auto III" and its sequels, Sega's own "Yakuza" series, "Fallout 3", and "Deadly Premonition". 21st century. "Grand Theft Auto" has had over 200 million sales. Creative director Gary Penn, who previously worked on "", cited "Elite" as a key influence, calling it "basically "Elite" in a city", and mentioned other team members being influenced  by "Syndicate" and "Mercenary". "Grand Theft Auto III" combined elements from previous games, and fused them together into a new immersive 3D experience that helped define open-world games for a new generation. Executive producer Sam Houser described it as ""Zelda" meets "Goodfellas"", while producer Dan Houser also cited "" and "Super Mario 64" as influences. Radio stations had been implemented earlier in games such as Maxis' "SimCopter" (1996), the ability to beat or kill non-player characters date back to titles such as "Portopia" (1983), and "Valhalla" (1983) and the way in which players run over pedestrians and get chased  by police has been compared to "Pac-Man" (1980). After the release of "Grand Theft Auto III", many games which employed a 3D open world, such as Ubisoft's "Watch Dogs" and Deep Silver's "Saints Row" series, were labeled, often disparagingly, as "Grand Theft Auto" clones, much as how many early first-person shooters were called ""Doom" clones". Other examples include "World of Warcraft", "The Elder Scrolls" and "Fallout" series of games, which feature a large and diverse world, offering tasks and possibilities to play. In the "Assassin's Creed" series, which began in 2007, players explore historic open -world settings. These include the Holy Land during the Third Crusade in "Assassin's Creed", Renaissance Italy in "Assassin's Creed II" and "", Constantinople during the rise of the Ottoman Empire in "", New England during the American Revolution in "Assassin's Creed III", the Caribbean during the Golden Age of Piracy in "", the North Atlantic during the French and Indian War in "Assassin's Creed Rogue", Paris during the French Revolution in "Assassin's Creed Unity", London at the onset of the Second Industrial Revolution in "Assassin's Creed Syndicate", Ptolemaic Egypt in "Assassin's Creed Origins", Classical Greece during  the Peloponnesian War in "Assassin's Creed Odyssey", and Medieval England and Norway during the Viking Age in "Assassin's Creed Valhalla". The series intertwines factual history with a fictional storyline. In the fictional storyline, the Templars and the Assassins, two secret organisations inspired by their real-life counterparts, have been mortal enemies for all of known history. Their conflict stems from the Templars' desire to have peace through control, which directly contrasts the Assassins' wish for peace with free will. Their fighting influences much of history, as the sides often back real historical forces. For example, during the American  Revolution depicted in "Assassin's Creed III", the Templars initially support the British, while the Assassins side with the American colonists. "" was developed by GSC Game World in 2007, followed by two other games, a prequel and a sequel. The free world style of the zone was divided into huge maps, like sectors, and the player can go from one sector to another, depending on required quests or just by choice. In 2011, Dan Ryckert of "Game Informer" wrote that open-world crime games were "a major force" in the gaming industry for the preceding decade. Another popular open-world  sandbox game is "Minecraft", which has since become the best-selling video game of all time, selling over 238 million copies worldwide on multiple platforms by April 2021. "Minecraft"s procedurally generated overworlds cover a virtual 3.6 billion square kilometers. The Outerra Engine is a world rendering engine in development since 2008 that is capable of seamlessly rendering whole planets from space down to ground level. Anteworld is a world-building game and free tech-demo of the Outerra Engine that builds upon real-world data to render planet Earth realistically on a true-to-life scale. "No Man's Sky , released in 2016, is an open-world game set in a virtually infinite universe. According to the developers, through procedural generation, the game is able to produce more than 18 quintillion ( or 18,000,000,000,000,000,000) planets to explore. Several critics found that the nature of the game can become repetitive and monotonous, with the survival gameplay elements being lackluster and tedious. Jake Swearingen in New York" said, "You can procedurally generate 18.6 quintillion unique planets, but you can't procedurally generate 18.6 quintillion unique things to do." Updates have aimed to address these criticisms. In 2017, the open-world design of "" was  described by critics as being revolutionary and by developers as a paradigm shift for open-world design. In contrast to the more structured approach of most open-world games, "Breath of the Wild" features a large and fully interactive world that is generally unstructured and rewards the exploration and manipulation of its world. Inspired by the original 1986 "Legend of Zelda", the open world of "Breath of the Wild" integrates multiplicative gameplay, where "objects react to the player's actions and the objects themselves also influence each other." Along with a physics engine, the game's open-world also integrates  a chemistry engine, "which governs the physical properties of certain objects and how they relate to each other," rewarding experimentation. Nintendo has described the game's approach to open-world design as "open-air".