[Guitar Woman]

Also, to be fair, I forgot to mention MP2's awful level design and agonizing puzzles. It's really really hard to play for more than 30 minutes at a time without the front of your head starting to physically ache, buuuuuuuuuuuuuuuuuuuuuuuut the redeeming features are the epicness of most of the boss fights and the great soundtrack.

Zero Mission and Fusion are also really good if you haven't played those, especially since they're both free.