Very polished game, the difficulty spike from level 4 to level 5 was a bit steep, level 9 was definitely a stumper but got there eventually. I couldn't make it past level 10. Seeing how simple the art was and the audio was, there was definitely plenty of time to make puzzles, a good choice in a game jam. The difficulty definitely needs a balance, other than that, maybe some music could be good. Overall pretty good unique concept and challenging puzzles, there isn't much else to critique on seeing how simple it is except the level design.
A good hooking simple game!