Hmm, may as well add in the few more I have, not sure if they have been said before.
Hawken - A fast paced mech fighting FPS game, really fun and can get intense, at least for me.
Path Of Exile - An Online Action RPG, similar to Diablo. I end spending a long time playing whenever I start it up.
Warsow - A fast FPS, set in a cyber world, blood and gore is non existent, and its open source and will always remain free. I dont play it myself, I just have it installed.
Warzone 2100 - An RTS game, based around being able to make custom tanks/aircraft using all the different weapons, hulls etc. Fun, but dont play against the AI, it creates way to many units, lagging the game.
Thats all i got right now, again I dont know if any of the games I said were said before. Sorry if they were. I cant remember.