S.T.A.L.K.E.R.: Shadow of Chernobyl, previously known as S.T.A.L.K.E.R.: Oblivion Lost, is a first-person shooter computer game by Ukrainian developer GSC Game World, published in 2007.
It features an alternate reality theme, where a second nuclear disaster occurs at the Chernobyl Nuclear Power Plant in the near future and causes strange changes in the area around it. The game has a non-linear storyline and features gameplay elements such as trading and two-way communication with NPCs. The game includes elements of role-playing and business simulation games.
The background idea and some terminology of the game ("The Zone", "Stalker") is borrowed from the popular science fiction book Roadside Picnic by Boris and Arkady Strugatsky and the 1979 film Stalker by Andrei Tarkovsky, loosely based on the book.