This game was great. I liked the idea of it. It was kind of hard to see how the theme connected to this game, but i think i get it now.
Just a few complains: The guitarloop kind of gets repetitive, maybe add like a proper song and let it reset everytime you respawn, cause having it constantly play makes it kind of obnoxious. The movement feels a bit awkard cause i didnt feel like i was moving at all, perhaps adding some shadows like some games do, or some background elements to make the movement feel like movement.
Now, the beats: The feel really off, it was really hard for me to concentrate on getting the beats right cause it was mostly watching the little circle instead of hearing for the actual beats. Try looking at a game like Crypt of the Necrodancer where beats are constant and it is easy to keep track of every beat because they were on sinc. Your game lacks that feeling and its a real shame.
I do see a future to this game as a real fully complete game on steam or the app store. Perhaps a bit of polishing here or there and you will be golden.
Overall, pretty fun game.