This is pretty incredible for a game jam entry. Mechanics, level design (and amount) and presentation are all superb. My only complaint is that starting at around level 2-4 I really would have liked an undo mechanic (which should be fairly doable outside a jam scope since you're snapping to half-grid positions anyway). I think I found a bit of cheese in 2-3 and 3-star, but nothing to take much away from the experience. Really fantastic work all around! :)