This was really fun. The concept was cool, the first introduction was interesting. A bit of constructive feedback I'd give though would be this.
- The "lava" or "lower ground" not sure what it is, that you can't walk on having the same texture is a bit disorienting so making it clearer which is which with a different texture would be nice.
- Some of the splits paths in the first bit did not work/were locked? Which was weird since it seemed to have 4 paths you could take. Maybe block off the ones you can't enter until they're unlocked?
- Having A as the "checkpoint" button ended up with me accidentally hitting it a bit, so maybe changing that to something else, or adding it to the pause menu could be helpful.
Otherwise though, the overall level design was nice, if with a pretty high difficulty curve. A couple more personal bits of feedback is that adding the use of WASD for movement would be nice. Either as a setting or possibly a shared default?