Thank you for your kind words :)
I did indeed tear my hair out creating the levels, testing different combinations over and over again, testing what's finishable and what isn't, testing different levels of difficulty, varying the mechanisms, and so on.
I would have liked more levels, but with the game's limited mechanics and the difficulty of creating levels, that's as far as I got.
But at least it's a finishable mini-game. And it's licensed free and open source, so anyone can improve it.