L4D2 demo, Borderlands, and TF2. Also the Source SDK.
Borderlands, awesome game, I got a rocket launcher that when it hits something it shoots out a bunch of mini rockets in all directions, three times until it stops.
In the span of three hours, I got a shotgun with exploding rounds, a silenced P90, then I got to fly a helicopter that can fire about 10 rockets every milli-second, got to blow up a boat with said helicopter, then sky dived off the tallest building in the game and landed safely on the ground with my parachute, then I drove A FUCKING TANK!
Welcome back Grand Theft Auto. We missed you.
borderlands. kinda boring. regret pre-purchasing it.
There hasn’t been anything boring about it yet. And I’ve been playing it mostly solo.
Lots of L4D2
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Call of Juarez: Bound in Blood.
Addicting.
bejeweled blitz on facebook.
Started 2nd playthrough on Borderlands. Level 37 and counting 
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Saw the video game.
A lot better than I thought it would be. Definitely a great rental. (no replay value and about 10ish hour game)
Only nitpick is the combat is kinda crappy until you figure it out. I absolutely loved the puzzles and the story though.
Half Life 2: SMOD
Who doesn’t think Half-Life 2 could have done with an explosive laser rifle powered by suit batteries?
Torchlight
Love at first sight
Stalker: SoC at full settings =D
L4D2 Demo, Garry’s Mod.
Aliens vs. Predator 2.
Hopefully I’ll be able to add Hammer and Colony 42 to that later tonight.
AVP2, that’s a good game. it does the series justice (unlike the movie with a similar designation)
I sure as hell hope SEGA gets their heads outta their asses and fixes the marines (backwards-assed copies)
Left 4 dead 2 demo.
TF2: Halloween edition.
TF2: Halloween Edition, and some moar borderlands.
Mass Effect.
I beat GTA: BoGT!