Liked this one very much! It could be a great start for a more hardcore game like Guitar Hero. Just need more shapes, more speed and explosions (obviously). The sound is very well placed, and I don't know how to explain it, but it has that "something" that traps you and you can't stop playing. Well done!
I also chose the "runner" mechanic to take advantage of the two button limitation, be sure to check out my game!