I really like your concept, and huge props for building it solo during the jam. Well executed theme and overall submission.
My feedback would be that its really difficult to see how my beat is going to actually line up in game. I think some kind of visual that would help me map where my guy is going to be at different points in the beat would be super helpful. Maybe having each column light up on beat (while planning), or having numbers on the columns that correspond to their beat would be enough.
I made it fairly far (I think) – to a level where you had to attack through barrels and pass through spikes while avoiding the laser shots and it just got a bit too much for me to keep track of by that point.
Overall, great job and congrats on the submission!