Its a three way tie between Deus Ex, for its great story, Freespace 2, for its great story and graphics, and the original QuakeWorld Team Fortress, the only game ever made that had perfectly balanced gameplay.
Hey, Sniper187, would you beleive that I managed to beat Resident Evil without using a *single* ink ribbon? I kinda had to since I didn't have any memory cards at the time....heheh.