This is among the small percentage of games, I have actually finished. In every way Deus Ex was (is) unique, from the enticing conspiracy-theory-driven narrative, through the way the story could be affected in ways, I had never experienced before (the possibility of saving Denton's brother was an eye opener), to the sense of absolute freedom and the amazing attention to detail.
Any shortcomings were forgiven, because the game was so exciting and it felt like the designers had though of every possible action I could take, however far out. The world just felt believable, delivering numerous memorable moments and looking back, there is just a special air of nostalgia about this game.