After recently playing Half Life for the first time and the Steam Summer sale recently ending I've come to the conclusion that I want to play these games (mainly the fps titles) in chronological order. Currently on Thief in the year 98 I've realized that I won't be able to play System Shock 2 for my 1999 games since it's not available on Steam. Now I own it's "spiritual successors" (Deus ex and Bioshock, which I haven't played yet) but I feel I should play this critically acclaimed game before I get to them.
So what I'm wondering is, does anyone know where exactly I could find this game since it doesn't seem to be available on Steam?