For the open source category, you'll need to have a README file and License file.
I spammed the buttons and managed to get a 25 streak. I might have broken the game, because then I wasn't able to hit any notes. It still showed my score going up, even if I wasn't pressing any buttons.
Great concept, I like that it's different instruments, but it's rather difficult to switch between the instruments and the notes... Maybe start with an "easy" (like easier than the easy mode) to get the hang of it. The music is lovely. You've got a good foundation for your game here. Nice job.