Wanted to play a second game on a second day before voting and the game save, well done!
The song play once also, I would not do 20 level on the same song, but only a few more song could help.
In term of puzzle, the first puzzles were easy, but the difficulty spiked a lot at 6. it may be me being dumb...
Would I enjoy more of this game concept? Yeah, I'm feeling the challenge and since the game save, it's easy for me to come back do one or two more levels from time to time!