No. 36: Portal (PC, also on 360, and PS3 Orange Box)
This was pure genius. Only a few hours long with a few bonus maps, but everything was sheer brilliance. The innovative portal gun, some inventive and mind bending physics puzzles and wonderfully funny. I played this on my own and went through the whole thing in a single sitting. A few weeks later I spent a few hours of a gaming session with some mates going through the campaign and simply laughing at their reactions. Pure gaming genius.
No. 35: Assassin's Creed 2 (PS3, also on 360)
I enjoyed the first, but it had its flaws. This fixed the flaws and expanded on the good things in the original. The free running, platforming and cool assassinations remained, but there was also a quality sandbox game with numerous activities, and a decently fleshed out story with enough mystery to keep things interesting.
No. 34: The Witcher (PC)
Oddly I got this game after a Zero Punctuation review (he hated it!). Everything he complained about I knew I would enjoy and I was right. The fantasy and magical world created by Adrzej Sapkowski is one filled interesting characters, deadly politics and ambiguous morality and this translated beautifully into the game. Unlike most Western RPGs where moral choices are almost clearly defined by good/bad/neutral (think Mass Effect wheel, Forgotten Realms alignment, Light/Dark side in SW), in The Witcher, your choices had major outcomes where there was no clear right or wrong. The way they handled the "adult" content was a bit weird, but otherwise, a superb WRPG. Can't wait for the sequel!