A really neat idea, I enjoyed the skewed perspective to show both levels, and how that actually became important once the "blocking" blocks were introduced. A few pieces of constructive criticism:
1. The player controller does not detect a jump if you've landed very recently. This caused quite a few missed inputs which always feels really bad.
2. Maybe make the black "instakill" blocks red instead? It took me a few tries to realize that was what was killing me, since they were the same color as the player I didn't suspect them.
3. Not sure if it was a bug or not, but on one of the levels, the main character fell through a hole in the floor during its run. Meaning the level couldn't be completed (which is where I stopped playing).
But overall, this is a really fun idea and little game, and I had a great time with it. Good job :D