To me, this game suffers from three flaws:
- the background makes it confusing, at it is sometimes hard to see what is a wall and what is not;
- the difficulty is really high for a "simple" game, maybe you should, not tone it down, but add simpler levels to begin;
- the music is very dark for what should be a light-hearted game.
Apart from that, great and challenging game, with simple mechanics and complex puzzles!