Since no one has mentioned it yet: "Beatbuddy: Tale Of The Guardians", a rhythm based music action adventure game that was made by a team of 8 people. It features a beautiful, hand drawn environment, 6 Levels with songs that have been composed for this game (Parov Stelar, Auston Wintory, Sabrepulse, ...) and many funny dialogues and characters. I was a tester for this game and I can tell you that it didn't get boring even after playing it over and over again for almost 10 months. (I just hope that this doesn't sound like I'm advertising it...)
Hey, I was sold on this game when you said Parov Stelar, but then I got to Austin Wintory and went out and got it. If you like rhythm games (especially in unusual mashups), you should check out [Crypt of the Necrodancer], a rhythm-based roguelike. It's not out yet, but I've been ogling it pretty hard, laying in wait.