I would say this is more of a toy or instrument than a game. Definitely a unique submission for this jam. Thank you for making this!
At first I was playing it on the web page but the menus were cluttered - once I opened it in full screen mode it got fixed.
It would be nice to be able to export to an MP3/4 file to listen to later. I found that you can convert a Unity Audio Clip to a byte array and export it using the “audio/wav” mimetype.
Maybe in a bigger version of this game it would be possible for players to share files, maybe even make it into a rhythm game?
Good luck!