Great ideas, I would love to keep refining this game and make it more of a full game experience. The very next thing on my plate that I ran outta time for was adding a early or late indicator, so your instinct is spot on.
As for mixing it up music wise, i had some logic to do half and quarter beats as well but i had to rip it out due to time constraints. I have a few more songs I will definitely add to this that i created prior to the game jam, but i couldn't use them to start since we are not allowed to use premade assets. So I wrote this one like 3 days before the jam ended, before that i was just coding it all to a click track. Those 2 weeks flew by for me!
Thanks so much for playing and also for the thoughtful feedback!