Great idea and nice graphical/UI polish. I'm a sucker for tower defense games, so this had me playing for a while. Took some time to figure out the right placement of instruments, and I was getting slaughtered for a while. Would've been nice to pick up from a checkpoint rather than starting over - or an easy mode - or a way to beef up health. The level 4 treble clef killed me, despite my army's ability to keep up on the previous level, so I'm not sure if that's a balancing issue or if I've got the wrong strategy. Also wish I didn't get 2-3 stores in a row on the map. Anyway, fun stuff. Great work for a jam!