Heh... I don't really have too many games, but between my computer, my other computer, my friend's computers, the school's computers, and just about any other computer I manage to get within two feet of (not to mention any consoles), I can normally be found playing:
SEIV
SEIII
==Solitaire
==Freecell
==Minesweeper
==(gotta love the free windows games
Conquer (think Risk, only not nearly as complex)
Tetris
Starcraft
Quake
Quake II
Quake III
Blood (quite bloody if you haven't played)
DukeNukem
Super Mario Brothers
Nibbles (AKA. "Snake", and many other things... depends who you ask)
Pong
Donkey Kong (the Atari one)
Q*Bert
Chessmaster
Utopia (Online)
Pinball (various Versions)
All the other games already mentioned in this thread and any games that will be mentioned after this post I would probably play if I had the opportunity. All of these are games that are even remotely electronic that I could think of in about two minute's time (which is why it's a bit unordered...). I didn't bother to try any other kind of game, because the list would just be too long
I'll play just about anything. I'm easily amused...