[Endoperez]

RPG: Betrayal at Krondor (free nowadays!), Baldur's Gate 1 (haven't tried 2 yet), Fallout 1 (same as with BGs)

Roguelike: ADOM, lately Crawl too
TBS: DomII, Dom:PPP, Master of Magic (I never really got into it, though)

RTS,FPS, MMO: Never found any I really liked, didn't get in Total Annihilation either... Probably I just don't like the genre

I also have X-com 1, The Ur-Quan Masters (Star Control 2 remake), DragonStrike and King's Quest 1 remake on my machine... Only the two first I _really_ like, others are just good. I would like to like Allegiance (also free), but haven't had time to try yet.