Made an account just to comment on this game cus I'm having so much fun playing it. So sad you can't push multiple boxes in a row....... it was such a nice solution as well. (not complaining btw, ik it's part of the game.) Really great levels, especially in how little time we had to make the games.
'Bug' wise, I think someone else mentioned it, but in the second level I accidently derailed the loop and (if you don't read the web page description) the sign that shows the undo button comes a little later on in that level. It's a very small complaint but I recommended the game to a few friends and they also got confused at that part and thought they broke the game.
Basically, in the future try make sure the tutorial is 'dummy proof', otherwise it might put players off when they don't know all the mechanics yet.
Other than a little saucier UI, and some unnamed levels, that's the only real negative point I have about the game which is pretty awesome. (Our game didn't survive the transfer to the web version...).
Hope it gets featured in the video!