S.T.A.L.K.E.R.: Shadow of Chernobyl is a first-person shooter video game by the 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 Exclusion Zone 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 video game and business simulation games.
[NOTE: a free old version, S.T.A.L.K.E.R. build 1935, is available here: http://clanbase.ggl.com/news.php?nid=311993 ]