I don't play them any more but I think two of the coolest games ever made were Star Control 2 and Syndicate. Half Life kicked butt, not just for the gameplay but for the mod community it inspired.
For you younger whippersnappers Syndicate was made by Bullfrog, Peter Molyneux's old company before he left to form Lionhead and make Black&White (the game where you get to potty train giant animals and sacrifice people from your email address book).
Best Free Game: America's Army.
Favorite Genre: Shooters, especially tactical ones like CS, Raven Shield, Ghost Recon.
Best Mod Ever: Rocket Arena for Quake 3
I didn't really get into Battlefield 1942, but probably because by the time I got it everyone I knew that played it had burned out on it after playing it for 3 weeks straight.
The office craze at the moment is Wolfenstein: Enemy Territory, but I'm guessing that with UT2004 hitting shelves this week we'll be seeing an improved version of the Red Orchestra mod released, with vehicle support. And that will truely rock