That was such a neat concept, blocks changing the shapes were funny but pleasing to look at. Also nice job on implementing slopes, they are impossible things to work on properly but in this case slopes did some visual improvements without being too janky in terms of gameplay.
Things went smoothly from stage 1 through 3, though I struggled a bit in stage 4.. Not sure if it's intended but that final stage seems to require memorization and blind experiments. I'd suggest adding indications for ground placements, which can be viewed before entering the door.