S.T.A.L.K.E.R.: Shadow of Chernobyl is free-roaming, RPG/FPS hybrid set in a near future in the devastated wasteland around the Chernobyl nuclear plant. Since the second Chernobyl incident in 2012, the area surrounding ground zero (nicknamed "the Zone") has been quarantined by the Russian army. The physical laws of the universe have been weakened in the Zone, creating dangerous disturbances ("Anomalies") and mutating the wildlife but also creating Artifacts, valuable items retaining some of the properties of the Anomaly that spawned them. Over the years, a lot of people have been drawn to the Zone, hoping to collect these Artifacts and sell them to the highest bidder. They are called Stalkers, scavengers roaming the wasteland hoping for a big find while trying to avoid the army, the bandits gangs and the different factions that claim ownership of the Zone.
The player's character is a Stalker suffering from amnesia. His only clue to his identity is a PDA with a single note telling him to kill another stalker.
The game is a free-roaming FPS with RPG elements. Players can explore the 30 square kilometers wide Zone as they wish, or accept missions from one of the numerous NPCs in order to increase their reputation. They need to take care of their equipment, as weapons and armor degrade over time, find or buy food, trade information, items or Artifacts with NPCs, and ultimately find out who they are, and the truth about the legends mentioning a strange Monolith at the heart of the zone.
The game was heavily inspired by the 1972 novella Roadside Picnic (by Arkady and Boris Strugatsky), and by the Andrei Tarkovsky movie Stalker (inspired by the same book and written by the Strugatsky brothers).