Excellent puzzle game, with a lot of very challenging and thought out levels; incredible for 3 hours!
As others have mentioned level 6 felt like a bit of an outlier; most of the later levels had some clear insights to have, but that one felt a little "bashy"; just do things until it works. Lack of undo also made some things tough (especially since sliding can have large, surprising effects), but undo is a tough ask for a 48 hour jam let alone a 3 hour one.
The graphics have a lot of charm and communicate the ideas well. Solid use of the theme. Overall excellent!