I recently finished S.T.A.L.K.E.R: Shadow of Chernobyl, which I have had in my Steam account since the 5th of January 2012. I don't know how it took me so long to put the hours into this game to finish it (and get the 'true ending'), because it really scratches the itch I have for alt-future/alt-history, has good worldbuilding, memorable moment-to-moment gameplay (even if the mechanics are somewhat broken in vanilla), has an I-have-to-know-how-this-ends story that I just got lost in constantly, and has left me on a Wikipedia deep dive about the Zone. Next up is Clear Sky, which seems to be the least favourite of the trilogy. I'm aiming to finish both Clear Sky and Call of Pripyat before getting into 2.