Thanks for playing the game!
I'm really glad that you enjoyed the visuals, since I am kinda an amateur at pixel art, so it's nice to hear that I'm going in the right direction :]
I had thought about implementing rebindable keybinds, but I never got around to it, which I now realize was a missed opportunity. As for the note clustering, it mainly comes from the slowing-down mechanic; the code can't keep up quickly enough and ends up spawning notes at their old positions. I also wasn't aware of the timer issue! Each timer length is set to the song's length, and I thought I had balanced it since the timer speeds up and slows down along with the player. However, after going back and playing it myself, I can clearly see that the song doesn't actually match the timers. Thanks for pointing that out!
The song idea and the notes on beat sound interesting, maybe I could cook up a level or too after the jam 🤔
Thank you for the insight :)