The puzzles were difficult and satisfying, the music and art is nice, the core mechanic is creative, and the game is surprisingly long for being developed in 96 hours. Very impressive!
One critique might be that an undo button would have been greatly appreciated. That way the player does not to restart an entire level if they make one mistake. Most of the Sokoban style games I have seen have this, so it felt weird for it to be missing.