S.T.A.L.K.E.R.: Shadow of Chernobyl, previously known as S.T.A.L.K.E.R.: Oblivion Lost, is a post-apocalyptic first-person shooter video game by Ukrainian developer GSC Game World.

The game uses a software feature called the "X-Ray engine". It features an alternate reality theme, where the second nuclear disaster happens at the Chernobyl Nuclear Power Plant in the near future and makes strange changes happen to the area around it, which create a lot of mutated animals, plants, and change the laws of Physics. The game has a storyline that lets the player have a lot of freedom, and features gameplay features such as trading and two-way communication with NPCs. The game includes features of role-playing and economic games.

Some phrases used in the game ("The Zone", "Stalker") as well as the idea of the game, are borrowed from the popular science fiction book Roadside Picnic by Boris and Arkady Strugatsky and the 1979 film Stalker, based on the book.

GSC Game World talked about the game's AI in January 2005. IGN said that the game, while similar to Far Cry, will have more wildlife, and that the way animals act in the game is as important to them as the humans. The animals anger will vary with how hungry and tired they are, as well as other things. So, the game will have some idea of fight or flight to it.

Gameplay 
In the game, the player is known as "The Marked One" who is a Stalker, a person who lives in the Zone and makes a living collecting "Artifacts" and selling them. The Zone has a lot of danger in it.

The type of game is a mix of a RPG and a FPS, though the player does not get attributes like Strength of Constitution, or get more powerful, which is different from a normal computer RPG. The role-playing part is mainly about normal RPG elements, such as storyline and the way other people in the game act with the player. But, the game does not let the player have a lot of choice when it comes to talking to characters in the game. Unlike RPGs such as Knights of the Old Republic, the number of different conversations the player can have with NPCs in the game is quite small and does not change the way that the game will end for the player a lot.

The Zone is made up of a 30 km square area, that has wilderness, human camps, and a few heavily-guarded military bases. But, the game world is not one big world, but is a lot of smaller maps broken up by loading screens. Moving from one area of the Zone to another can only happen at certain passageways; a white fence border stops players from trying to cross the map in any other area. The game does not have vehicles that the player can drive. The player does have a fast sprint, but he or she cannot sprint without stopping, and the player can not fire weapons while sprinting

Bullet physics 
S.T.A.L.K.E.R. uses "realistic" bullet physics, that is, the way that the bullets move is like how a bullet would move in real life. The bullet physics are similar to tactical shooters such as Ghost Recon Advanced Warfighter or Call of Duty 2. Bullets are affected by gravity, and weapons are highly inaccurate when fired "from the hip". To be sure of hitting the enemy at long range, players must aim using the iron sights on their guns. Also, bullets do "realistic" damage, and the player can die after only being shot a few times (but to make up for this, later in the game the player can get different armor suits that increase the amount the player can be shot before dying).

Artifacts 
"Artifacts" are the product of 'anomalies', which occur randomly throughout the game. Anomalies are normally a few metres across, these areas are dangerous to enter and can instantly kill the player or cause serious injury. They can be seen by looking for swirling leaves, heat waves, wind moving about, and electricity. An anomaly will be in the game for about one week in game time, and once they have disappeared the player is able to collect the artifacts left behind, which can be traded for supplies, or worn to enhance some player abilities, with normally some bad side effects; for example, there is an artifact in the game that can make bullets less likely to hit the player, but will slowly give the player radiation sickness, which will eventually kill the character being played.

Mutants 
The local animals and plants were altered a lot by the years of radiation. They have become more dangerous, and have developed natural defenses to survive the harsh world. There are also a lot of people that were mutated by the radiation from the second explosion in the power plant.

Human factions 
The stalkers find it difficult to hunt for artifacts because the Ukrainian Military is in the area, trying to stop the zone getting bigger, and help control the mutant. The Military is an enemy of anyone who is not Military, and will work as a big team to attack anyone they see using heavy force and the use of Mi-35 Hind gunships, which are attack helicopters.

A few other groups work in the zone, and are neutral or an enemy based on certain events. Two groups are important: "Freedom" and "Duty" as they are the only two groups that the player can decide if they want to be friendly towards or not. Neither Faction will attack the player at first, and both will offer missions to the player. Freedom and Duty are at war with one another, and although th player can keep friendship with both of them at first, the player will end up having to choose a side. The player cannot join either faction, no matter how friendly the player becomes towards them, as the player's faction status in the player's P.D.A. will tell the player, the player is always a loner in this game. There are several other groups, these are almost all enemies for the player. The scientists are different though, because the player can be friends by saving one of them from a mercenary attack later in the game.

The player also works with other NPCs in the Zone, and can help Stalker factions and receive missions, which further the storyline. Players are able to explore over 30 square km of the Zone, including the ghost town of Pripyat and the empty Chernobyl Nuclear Plant, while meeting animals and plants mutated by radiation as well as other Stalkers and NPCs.

Technical features

Artificial intelligence 
The game uses uses GSC Gameworld's proprietary ALife artificial intelligence engine. ALife supports more than one thousand characters living in the Zone.

The NPCs act as if they really are alive, having different states, such as task accomplishment, combat, rest, feeding and sleep. The monsters in the game also act in this way. These monsters will move in large groups. The non-scripted way the characters work means that there are an unlimited number of random quests. For example, rescuing Stalkers from danger, killing Stalker renegades, protecting or attacking Stalker camps or searching for treasure. The AI characters travel around the entire zone as they want.

Numerous different ways of playing the game can be used, such as using stealth and sniping. The NPCs will react in a different way to each of them.

Weather 
A weather system works in various parts of the landscape and let the weather act as if it is real, letting the game have weather such as sunshine, storms and showers. The weapons available, the way the AI acts, game tactics and ranking systems will depend on the weather.

Multiplayer 
Multiplayer, like many other new games, will work over both LAN and the Internet with up to 32 players. Currently the three game modes are Deathmatch, Team Deathmatch and Artifact hunt. The game will also use a ranking system.

Initial concept 
Early in the development of the game it was named Oblivion Lost, and the game was planned to have more of a futuristic theme before the idea was reworked to set the game in Chernobyl, being a nearby location to the game's Kiev based development team. Eventually, this was reflected in the change of the game's subtitle to Shadow of Chernobyl. Screenshots and trailers of this early version can be found on various web sites, depicting the robots and spacecraft originally planned for the game.

While the source of the Zone may still turn out to have extraterrestrial connections (like in Roadside Picnic, where the Zone is thought to have been an absent-minded, accidental creation of a careless, vastly superior alien race), there is no indication that such more direct manifestations will return.

Development delay 
The game was first announced in November 2001 and has had its release date, originally in 2003, pushed back several times. Meanwhile, hundreds of screenshots of the game have been released, as well as dozen preview video clips, accompanied by other forms of promotion by GSC, such as inviting fans to their offices in Kiev to play the current build of the game. However, due to the delays some considered S.T.A.L.K.E.R. to be vaporware, like the game Duke Nukem Forever, or fear that the game may become a new Daikatana.

In their E3 Awards for 2005, IGN gave S.T.A.L.K.E.R.'s absence the award of "Biggest PC Surprise"; the runners-up were the absence of Fallout 3 from the show, and the lack of a new announcement from Blizzard Entertainment.

In February 2005, THQ expressed desire to see the game released toward the end of its 2006 fiscal year (March 31 2006) but maintained that no release date had been set. In October, 2005, THQ confirmed that S.T.A.L.K.E.R. will not be out "until the second half of THQ's 2007 fiscal year - October 2006 at the earliest." In February of 2006, THQ revised this possible release window, saying the game would not be in stores until the first quarter of 2007.

In an interview at the Russian Gameland Awards, PR Manager Oleg Yavorsky indicated that release was planned for September 2006.

In 2006, the game came 9th in Wired'''s Vaporware '06 award.

THQ ran a competition in January 2007 offering the lucky winners the chance to play the beta version of S.T.A.L.K.E.R, in a 24-hour marathon session. The event, scheduled to take place on the January 24 2007, was subsequently changed to a 12-hour session days before it was supposed to occur.

On the morning of the event, the 'lucky' winners were met at the venue by the THQ staff that had organized the event, who were embarrassed to report that they had been unable to get any copies of the game. In late February GSC managed to release a public beta. Multiplayer demo was released to public on March 15 2007.

On March 2 2007, it was announced that the game had gone gold.

 Reception 
So far, publications which have reviewed the title have been largely positive, noting the immersive, atmospheric setting and open-ended, rewarding gameplay. Some aspects of the game, such as the translation of printed text, the absence of subtitles for spoken Russian, and general game performance, have received negative criticism. It has also been noted that there are numerous sporadic bugs which can affect gameplay, although most of these are considered minor. However, in the newly released patch 1.0001 it is claimed that many bugs and glitches were fixed. Another common criticism is the fact that less than half of the map is actually accessible by the player.

Publications which have submitted reviews include IGN U.S. (8.2/10), IGN Australia (8.9/10), GameSpot (8.5/10), Australian PC User 95% and PC Gamer'' (87%). Ukraine's own Gameplay magazine awarded it 4.5 out of 5. UK based website Mansized  scored the game 4/5.

Plot 
Several years after the Chernobyl disaster, the Zone was occupied and "repurposed" by several research projects run by the Soviet government. Facilities were constructed or expanded under the abandoned military bases and civilian factories and industrial sites in the area, and a large lab was established directly beneath Reactor 4 and its Sarcophagus. These experiments were focused primarily on various aspects of the mind, including creating and enhancing ESP in humans, psychotronic weapons, and an experiment intended to create a human hive mind: the "Collective Consciousness," or "C-Consciousness," project.

Shortly after C-Consciousness was successfully created by the fusion of seven human minds through a computer interface, the Soviet Union collapsed. In the years that followed, some of the research labs were abandoned, and the C-Consciousness entity took greater control over the few facilities that remained in full operation. With its enhanced cognitive abilities, C-Consciousness was able to perceive and eventually to directly alter the "noosphere" (the collective "environment" of all thought, just as the "biosphere" refers to the sum total of all biological matter and its myriad interactions).

The intention of C-Consciousness was subtle mind control on a global scale. It believed that by manipulating the noosphere that the more negative and destructive aspects of human consciousness, cognition, and emotion could be eliminated to create world peace and harmony. Unfortunately, in 2006 C-Consciousness's first major attempt to manipulate the Noosphere resulted in disaster. There was a massive explosion of both psychic and physical force, and the noosphere in the vicinity of the C-Consciousness lab was twisted and distorted. In much the same way that the biosphere can permanently alter the physical landscape of the earth, so manipulation of the noosphere can distort all manner of physical reality: mind over matter on a massive scale.

This distortion of the noosphere powered by C-Consciousness and the machinery it was connected to created the anomalies and many of the mutants that inhabit the Zone in 2012. Desperate to correct its mistake and in order to shield itself from outside interference, especially the meddlesome "Stalkers" beginning to appear in the Zone, the C-Consciousness created an "Alien Monolith" in the center of the gutted Reactor 4, and used its ability to affect the minds of normal humans to create the "Monolith" cult, a group of heavily armed zealots whose tenets included worship of the Monolith and the prevention of "heretics" from approaching the remains of Chernobyl. They converted the Steel Yard radar facility near Pripyat into a powerful "Brain Scorcher" that would blast the mind of any unprotected human who approached too close, turning them into mindlessly aggressive zombies (while allowing C-Consciousness to select some individuals to brainwash into new members of Monolith). Finally, they used some of their agents (former Stalkers spread throughout the Zone) to disseminate stories of a "Wish Granter" at the heart of Chernobyl, ensuring that anyone who did manage to evade both the Monolith faction and the Brain Scorcher would be drawn to the Monolith and disposed of, rather than discovering the existence of the C-Consciousness lab.

This lasted for several years, but the continued efforts of C-Consciousness were unable to repair the damage they had done to the Zone. In fact, the damage appeared to be getting worse, with "Blowouts" deepening the distortion of the noosphere around the Zone at irregular intervals. Still, the C-Consciousness entity persisted in its experiments, behind the shields of the Monolith and the Wish Granter myth, the Monolith faction's patrols, the Brain Scorcher, and the dangers of the Zone itself. Occasionally, though, special circumstances would require an agent, a human able to do what was needed to preserve the Zone's secrets without revealing the existence of the C-Consciousness project. In these cases, Stalkers who were tough and resourceful enough to make it to or past the Brain Scorcher would be captured, brainwashed, and sent back into the outer areas of the zone on one of the "Death Trucks." These agents were marked with the tattoo "S.T.A.L.K.E.R." This is where Strelok, the main character, enters the story.

Strelok and his allies, Ghost, Fang, and Doc, were a group of Stalkers who had a particular interest in what exactly lay at the center of The Zone. At some point a few weeks before the start of the game, they managed to slip past the Brain Scorcher and all the way to the Nuclear Power Plant, finding the Monolith, an electronically locked vault door beneath the Monolith chamber (which leads to C-Consciousness), and documents hinting at the fact that the giant glowing Monolith was in fact a deliberate trap for anyone attempting to discover the secrets of the Zone. Unfortunately, they were forced to retreat, and their next attempt to penetrate into the heart of the Zone met with disaster. They had managed to obtain an electronic lockpick that would open the vault door, but this time the Monolith was ready for them and they were forced to retreat again, and their escape was further complicated by a blowout. Strelok was caught in the blowout and rendered unconscious with a severe case of amnesia. This made for a perfect subject for the conditioning process for a human agent of the C-Consciousness entity. Ghost and Fang escaped, but Fang was seriously wounded and died before the pair made it out of Pripyat, with Ghost moving on to find "safer" work in the outer regions of the Zone.

By this point, Strelok had become a serious threat to the security and secrecy of the C-Consciousness lab and the entity contained there, and it was decided that Strelok must be killed. However, due to unknown factors, C-Consciousness made a mistake: not realizing the identity of the man who had been caught in the blowout, they attempted to program him to kill Strelok, when in fact the man was Strelok. A second accident, the chance destruction of the Death Truck meant to carry this new agent back to the outer Zone, resulted in a loss of C-Consciousness control over him. Strelok was a free agent once again, though confused, amnesiac, and stripped of his possessions. The mission to kill himself led Strelok to retrace his steps through the past few weeks, tracking down his old associates and, over time, putting back together the evidence that had led him to become a danger to C-Consciousness in the first place. With the help of Doc to reveal his identity and to point him in the direction of a backup cache of documentation and another electronic lock pick, Strelok returned to Chernobyl and penetrated to the chamber under the "Monolith," destroying the projection device that created the illusion.

C-Consciousness, having no other option, confronted him to offer an explanation of their actions, the nature of the Zone, and a choice: to join them, bolster their numbers, help them repair the harm they had caused and shepherd humanity's consciousness towards peace, or to face a final confrontation with the remaining forces of the Monolith Faction in an attempt to reach the heart of the real C-Consciousness Lab, in order to put a stop to their manipulations and machinations.

References

Other websites 

 Official website
 THQ's Official S.T.A.L.K.E.R website
 GSC Game World's Official website

Windows games
THQ games
2007 video games
Shooter video games
Horror video games