The Wonderful End Of The World, it came with the potato sack, I downloaded it and haven't played it.
Diablo 2 was unplayed, but I eventually deleted it out of pity.
I played like 5 minutes of The Maw and left, I think because of horrible engine issues that gave me insane lag when it really shouldn't.
Cogs because it sucks
Braid because it sucks
The Ball for some reason
All the Counter-Strike games besides Source are about to get this, I just got the Valve Complete Pack.
Day Of Defeat nonsource, Source version is fucking amazing and the original is probably gonna die in a cyberhole.
Defense Grid because it sucks
Half-Life: Source because I downloaded the nonsource edition and can't be assed getting it aswell.
Mass Effect because... something.
Mass Effect 2 because I haven't finished the first (and probably never will)
Left 4 Dead because the second is infinitely better.
Fallout 1/2 because they suck
Fallout 3 because I have a swarm of games to play and it's my main backup.
ProtoGalaxy because it sucks
Ricochet because I'll never get around to playing it.
Spiral Knights because I can't be bothered.
Terraria because it hates me.
Toki Tori because it sucks
Trine because too many other games.
UT3 because I can't be bothered redownloading 8gb I ultimately won't use that much.
Seiklus because it sucks
/list.