Really good concept with nice execution. The levels are fun, small and don't overstay their welcome. I sometimes felt that I've solved it more easily than was intended by creator, but that's a minor stuff. There's a small bug with the box: you can throw it out near the border of the level and it falls out, after that there's no way to pick it up. Again, that's a really small one for a game jam entry.
Good stuff!