S.T.A.L.K.E.R stands for Scavengers, Trespassers, Adventurers, Loners, Killers, Explorers and Robbers.
In the game's alternate history, a second meltdown occurred at the Chernobyl nuclear plant in Ukraine in 2006
S.T.A.L.K.E.R. "Shadow of Chernobyl" is the first game realised from S.T.A.L.K.E.R. franchise.
Stalker's build engine is known as The X-Ray engine.
Originally titled S.T.A.L.K.E.R.: Oblivion Lost.