Hmm... my favourite games... I'd have to say that I like a lot of them, but my top 10 are (in no particular order...):
1) Legend of Zelda (Twilight Princess, Ocarina of Time)
2) Super Mario Brothers (Super Mario Sunshine sticks out to me, but I love pretty much all of them, including the old ones, on the NES and SNES.)
3) Brawl. Super Smash Bros. Brawl. (I love that game. Fights!)
4) Harvest Moon (farming made fun!)
5) Kingdom Hearts (I somehow like Roxas a tad better than Sora)
6) Ace Attorney series (Phoenix Wright! Court! WHEE!
7) The World Ends With You (as far as I know, it's just a single game, with a small chance of a sequel, but I loved this game to bits. It occuppied the majority of my summer last year...)
8) Pokemon! (it sounds so geeky, but I still like them. The first ever games have the best pokemon.
9) Little Big Planet. (So many great ideas incorporated into the game, and it really includes laws of physics. It makes it really realistic to play).
10) Animal Crossing (it's cute.
I get fairly obsessed into them when I start playing them. They're really addictive.