I bought it for about $10 bucks a little earlier in the year (Spec Ops that is) and have been thoroughly surprised by how much I have enjoyed it. I'm 2 chapters from the end (hope to actually finish it today/tomorrow) but it has definitely been worth it for me. A great surprise for this year.
I'm definitely buying this on PC, but I have a backlog of about 1 bazillion games, so I'm gonna wait until the inevitable steam holiday sale to pick up this, Borderlands 2, and maybe Darksiders 2 if I beat the first one by then.
Mine was Psychonauts if you don't include the Orange Box that started it all. Actually, I had HL2 way before the Orange Box, but didn't realize you could gift extra copies so I gave my old steam account to a friend and started a new one with the Orange Box. Owell, I think after more than 140 games its a bit too late to trade accounts back :P
I think all of the 2D Castlevania games are pretty damn amazing. I can discount the 3D ones, right?
Mine is definitely Casltvania as well, but why hate on the 3D ones? I actually really liked Lament of Innocence, Curse of Darkness and had enough fun with Castlevania 64/Legacy of Darkness (yeah I bought both). Plus Lords of Shadow was great! Maybe I'm just a bit of a fanboy though :P