PC. Portal 2, Half-Life 2, Left for Dead and Team Fortress 2.
GRAW 1 and 2, MW1 and 2, Halo Series (Xbox 360), various command and conquer versions on PC. Minesweeper. I don't play as many games nowadays as I wish I did.
By far my favourite game is Advance wars. I play mine on a 3DS XL. In 2D :p
MMORPGs on my Windows box.
WoW, Diablo3, StarCraft 2 all on my iMac
Battlefield 3, CoD and such on my gaming pc
Pro Evolution Soccer and RockBand on my PS3
Oh my, I have loads, off the top of my head I love(d) the Gears of War series. I have an XBox 360 :)
I am mainly a PC player. My favorite game will always be Age of Empires II : The Conquerors. I spent so many hours on it I can't count them.
I also play currently Starcraft 2 (RTS Fan) and Lineage 2 (MMORPG)
i'm not gaming.
I'm not much of a gamer. I like simple games that I can play for at most half an hour when I'm taking a break to ponder a problem. So, puzzle solving games are what I normally end up playing (portal, osmos, etc)
I never got into the console world and as such, I can't really handle console controls very well. My native controls are mouse and keyboard (for gaming - I try to avoid the mouse as much as I can for normal computer use)
I love lots of genres of games, and I enjoy many platforms.
Favorite genres are probably:
Platformers - Rayman Origins, Psychonauts, etc.,
3rd person action - Prince of Persia Sands of Time
Action RPGs - Legend of Mana
First Person Shooters - Half Life 2, Quake
I love my PC, Nintendo DS, Xbox 360, Wii, SNES, NES, and others.