Cute game!
I did find some levels that were not solvable though, that would be the first thing on my whishlist to fix,
but if that'd be too hard, I would also be ok with having a more accessible restart button (not hidden in a menu) to make it easier to recover from that state.
That being said, the core mechanic feels like a Hanoi tower on steroids, really fun little concept, I could see this work like some kind of candy crush phone game!