Cool concept! I enjoyed getting into the rhythm once I figured out the rules. I agree with of of the other feedback about wanting some time challenge, for the last level i basically just focused on the swap button that was right before the square, and paused until the right color came in the row below, then swapped, unpaused, repeated. If you couldnt pause and you had a little box/cursor you could move from swap point to swap point with arrow keys then press space to swap instead of clicking buttons, I think that would get super chaotic and fun. Well done!