I like the concept and the gradual introduction of new features! The game is already well put together with a lot of levels. The solutions were a bit easy to figure out from looking at the level and counting out the spaces, though. It might be cool if there were multiple correct solutions. Since you're making the music, maybe more complex and intricate beats/rhythms could be rewarded somehow (i.e. a rating system or something)? Nice job! And I like the squishy animations on the box.