In no order:
Portal (PC) - Funny, fun, and brilliant. The game was just a blast to play and a few amazing hours of gaming.
Super Smash Bros. Brawl - Fast, fun, and among the most balanced and diverse fighting games I've ever played. Just a joy to play.
Super Mario Galaxy - Made me feel like a kid again. I've rarely had more fun in my life.
Ace Attorney (franchise) and Professor Layton - Brilliant, hilarious, touching, and unique. Challenged my perception of what a game could be. Both games challenged your mind instead of your thumbs, and through great and fun characters led to hours upon hours of entertainment.
Ratchet & Clank Future: Tools of Destruction - In my opinion the single best HD console game bar none. Just a blast to play.