This is really well-done. Adorable graphics, great use of light and darkness, puzzles that make the player think.
I must admit that the game stumped me pretty quickly, though. I cleared the screen to the left of the start screen... then I managed to clear the screen to the right, but... for the life of me I couldn't escape.
Obviously this is a design choice, but I found myself wishing for the type of one-way platforms that you can jump onto from below, a la Contra. :)