Beat Hazard. A remarkably simple game with no story, just playing asteroids on acid, powered by music. And considering the wealth of music out there every new song is effectively a new level.
As for AAA titles, Dragon Age Origins. Must have done 4-5 characters and thanks to the skip the fade mod I never find it gets too bad. Plus the ending is still on of the best i've ever played. Pity they murdered the franchise with 2.