Cool game. It's obvious that you learned a lot about rewarding-systems.
An easy thing that would greatly improve your game (in my opinion) would be using a color-palette. I think your game is pretty dependent on colors.
The gameplay itself doesn't fit the theme of the jam, but is pretty fun. I found myself playing more often than I wanted :D
You nailed the use of audio with rewarding sounds & fitting bg-music! That's a thing I still need to improve for me. Overall, this is a great game considering the short dev-time