Intruiging concept, and I really like it as a way to incorporate the limitation. The last puzzle in particular was challenging, a felt really rewarding to solve.
I found the combination of the moving background, the ambient noise and the 'bong' noise when you beat a stage to be deeply relaxing, which I always appreciate in puzzle games like this.
Would love to see some more stages, and although the undo button is great I'd love to have the option to fully reset a stage to avoid repeated tapping when I knew I messed up a while back.