This is a very "jam" concept and I'm delighted you went all in on it. The result feels very unique and I enjoyed solving the navigational puzzles.
You may want to adjust so that it world swaps only on jump, not on button press. You can swap while in air.
I didn't finish because the amount of progress you lose by falling made me give up.
I didn't enjoy the part of this where I got stuck in floors or walls, but that's a tricky issue to solve if you want terrain to be different between the worlds.
Also, great lighting. 👌