As a result, the physical, chemical, and biological processes in the area were altered, spawning numerous nature-defying anomalies, artifacts, and mutants.

The player takes the role of a "stalker" - a name given to trespassers and adventurers who have come to explore the exclusion zone and its strange phenomena.

Due to the experiments conducted in these laboratories, a second catastrophe occurred in 2006, which caused physical and meteorological phenomena all over the exclusion zone and mutation of local plant and animal life.

[2] After the second disaster, the Zone grew rich with anomalies — inexplicable phenomena that do not obey the laws of physics.

[3] The anomalies are causing artifacts to appear, which are items with unique and extraordinary properties such as anti-gravity or radioactivity absorption.

Additionally, military squads carry out operations in the Zone, such as elimination missions or securing strategic points.

Typically, every game's primary goal is to reach the center of the Zone, with a number of adventures, dangers, and challenges on the way.In the first game, the player takes on the role of an amnesiac stalker referred to as Mecheniy, or the "Marked One", tasked with killing another stalker named Strelok, or Shooter from Russia.

The protagonist uncovers clues to his past and true identity while helping other stalkers and encountering dangerous mutants.

Shadow of Chernobyl features seven endings which are dependent on multiple factors such as money earned, supporting certain factions, or how much of the protagonist's memory was pieced together.

The player assumes the role of Scar, a veteran mercenary and the lone survivor of a huge energy emission he was caught in while escorting a group of scientists through the Zone.

He is rescued by and ends up working for a group calling themselves the Clear Sky, who are dedicated to researching and understanding the nature of the Zone.

The player can choose to have Scar side with or against certain factions in the area to help achieve Clear Sky's goal.

Having discovered the open path to the center of the Zone, the government decides to establish control of the situation through Operation Farvater (Fairway).

This includes sending a number of reconnaissance helicopters into the Zone before dispatching the main military force thoroughly.

As a result, the Security Service of Ukraine deploys former stalker turned military operative Major Alexander Degtyarev into the Zone to investigate.

[11] In May 2018, Sergey Galyonkin, the creator of Steam Spy, tweeted that GSC Game World would create a S.T.A.L.K.E.R.

In 2015, they released a free-to-play massively multiplayer online first-person shooter game titled Survarium in the spirit of the franchise, using ideas they created for the cancelled sequel.

The game features similar gameplay and themes to S.T.A.L.K.E.R, and the environment is based on the real Chernobyl exclusion zone, done by utilizing photogrammetry measurements.