This is superb, and wonderfully original! I was pleasantly surprised not only at how difficult the puzzles were, but also how addictive they were. Like others have said, there can be a bit of "guess and check" at certain points, but there's an odd amount of intuition that seemed to build up for me. It's already very very nice, but perhaps it could be even better with a bit of ambient background music and a few hints or guide rails for the more difficult levels.
Nice work!