5 - The Legend of Zelda: Twilight Princess
It's Zelda, so I like it. Next game better be more progressive, though.
4 - Super Smash Bros. Brawl
Hell yeah, it's Brawl! It's awesome, but not legendary(for me the Smash series never was)... nevertheless, still my most played game of the generation yet.
3 - Mass Effect
Though I haven't completely finished it yet, Mass Effect combines the deep epicness of the RPG-genre with the pick-up-and-play gameplay of the shooter-genre. This gave me the opportunity to enjoy a non-Nintendo RPG for once, and that turned out really good!
It's absolutely great to be emotionally involved with the characters in a game to the point that you feel really, really good when you save a life, and to feel really bad when you fail to do so. In game, I went back to an earlier point in the game to do certain things better a couple of times, that says enough I think.
2 - Bioshock
Bioshock is without a doubt in my mind one of the best games ever made. Everything about this game is great, and I love the setting. There's only one game this gen that's even better, and that is...
1 - Super Mario Galaxy
The first of a breed of modern classics that can be enjoyed by nearly anyone, cores and expanded audience alike. It's some of the purest platforming gameplay ever, and yet still so fresh! And what about the variety of different mini games and tasks? Super Mario Galaxy is the Super Mario Bros. 3 of 3D-platforming, now let's just hope that Nintendo will release the Super Mario World of 3D-platforming in a couple of years as well.