Visuals
1 ... I do not like those buttons (GUI) -> one of reason is they looks like map/world elements
2 ... try different color adjustments
3 ... add mouseHover/mouseClick button feedback
4 ... decrease size of buttons for full HD/or option turn of mobile mode
5 ... tune <look direction of character> -> character look where its going to
Design
1 ... this up/change gravity very good design
2 ... falling out of map not visible (no visual feedback except you died -> reset):
2.1 . add danger zone feedback
3 ... swapping bg color very good
4 ... how would look fully connected floors/walls?
5 ... maybe scale character when using direction swap with camera zoom to give extra impact of core ability/game mech.
Controls
1 ... controllable +2
2 ... maybe adjust tweens/interpolations (how speed changes)
Sound
1 ... it fits theme as chilling sound
2 ... maybe adjust tempo based on bg color
Bugs
1 ... player is able to go behind the map -> when you realize it you are force to restart (cause its too late)