Games/Series you recommend are MUST PLAYS at least once in a Life time?

[mornelithe]

Given that most of the easily accessible franchises will already have been mentioned, I'll go with one of my top 2 FPS' of all time. S.T.A.L.K.E.R. - Shadows of Chernobyl, and Call of Pripyat. Two of the greatest FPS' ever made.