I just finished up my very first play through of Deus Ex. A pretty good game, though I didn't think it was quite as great as everyone said it was (though maybe it was because I played it 10 years later).
The real niftyness shows up when you play it again, and do everything differently. Will Sandra reconcile with her father, or run away and become one of the bums at the gas station? Or will you even save her at all? Will Paul survive or die? When will you choose to kill Anna-----you have at least 3 different options on that score? Where will you fight Walton Simons: in the undersea labs, or at Area 51? Will you find an entire area of Hong Kong you completely missed the first time?