Really nice!

I wish you didn't have to use the mouse to hit next level or restart, I was surprised when enter and R respectively didn't work for that, and sometimes the levels clip off the top of the screen a bit, but this is really excellent. Very playable and great. Simple, nice, elegant.

Beyond those two issues, the only other thing that could really improve this game beyond fancier graphics/sound (which is a never-ending prospect and totally understandable for a game jam) is the ability to hit Z to infinitely undo. Then it would be a proper sokoban game almost ready for a professional release with tightened up visuals/audio and more levels. There's little that needs to be added for this to work as a professional game.

Nice work!