S.T.A.L.K.E.R.

  S.T.A.L.K.E.R.: Shadow of Chernobyl came at a time when I really needed something great to play.  I was getting bored and was one of those insain Fallout fanatics waiting for Fallout 3 to come out.  Stalker was the answer to my boredom.  Eef waiting for Fallout3! STALKER had it all, Amazing visuals, great action, great atmosphere with an immersive world and story.
The game borrows from the book Roadside Picnic (which I am reading right now) and the film Stalker (Also based on the book) and takes place 20 years after the Chernobyl incident where a second disaster occurs creating "The Zone".   You play the role of a STALKER who is repaying a debt to the man who saved you from an accident that left you amnesic.  After which you go on a mission to find out who you are and what you are doing in the zone.  The only clue is on your PDA containing the message, "Kill Strelok"
If you like FPS's with RPG elements, you must play this game.  Especially if you need your post nuclear fix.