The puzzles are quite nice, but I would prefer a more responsive movement system where if you hit the left arrow key you move left immediately rather than having to turn left then press it again. Also the undo key doesn't seem to undo block pushes? It just undoes movement
You might want to just face another direction to do an action without actually moving (into a laser beam or a crumbling floor tile for instance), so it is needed. You might like the mouse control more, though you have to be careful. A mix of both does work.
The undo key does undo block pushes but also any other move for the same reason (it also works if you're accidentally hit by a laser beam and die).