Ah the perennial fave thread.
Impossible task.
So I'll just name three games that come to mind that have given me great satisfaction playing them. Ask me tommorow and I'll probably list a different three.
RACING DESTRUCTION SET - C64
I'd love to see a new version of this on Xbox Live Arcade. Hi-Res graphics, but same identical play.
TEAM FORTRESS CLASSIC - PC
Like most TFC fans, I feel like Valve's Man in the Iron Mask - TFC imprisoned in their basement, shunned by Gabe Newll in favour of crap like Day of Defeat. For shame Vavle. Where's our fucking TFC Source / TF2?!?!
RIDDICK - Xbox
Starbreeze know how to push the Xbox like no other (see Enclave). Awesome game. Their 360 stuff should be mindblowing.