Extra point 5 for level 5.
5. The red wall inverses controls mechanic feels unfun. There's no room to adjust yourself, the moment you go through the red wall there's a second red wall going right at you, and you accidentally go the opposite way you want to and die. The mechanic itself is cheap, too, unlike the perspective changes. Any game can be made harder by messing with the controls.
Addendum to 4. Instead of restarting at a hexagon on the 2D perspective, stay at the shape and perspective before the restart? That'd prevent confusion, while not giving you the thought that you're starting on square 1 again, you're just continuing from where you died.