Interesting little puzzle game. I think it could work well as an mobile game with touch controls (only tried on desktop). I got stuck on level 11 with my limited brain power at the moment. But enjoyed the puzzles before that. A bit of "juice" would add a lot to this game I think, some small visual effects on painting and some "fireworks" on finishing a level.
I had the issue that I had to play the game on keyboard, but then switch to mouse to goto the next level. Which isn't great for usability.
Next to that the "next" button for some reason is "nex". And I had a crash on finishing level 10, where the game would no longer respond and there is some null pointer exception in the developer console.