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 NPC. The game includes elements of role-playing and economic games. Some terminology of the game ("The Zone", "Stalker") as well as the background idea is borrowed from the popular science fiction book Roadside Picnic by Boris and Arkady Strugatsky and the 1979 film Stalker, loosely based on the book. Some of the music in the game such as that heard on the radio or sometimes performed by stalkers with guitar