This is a hard game! Absolutely unforgiving from the controls to the collision boxes. The slightest touch on a spike immediately destroys the player character. Thankfully, respawning is well implemented and after getting the hang of it, becomes very satisfying to finally pull though another set of spikes. A quick look at the code showed that the physics are frame-rate dependent, which basically made it super fast on my PC. You might consider using frame-rate independent physics to ensure that everyone's experiences are roughly the same regardless of the computer power they're using.
The choice of using the up button to jump is questionable albeit fair. I would prefer using the space bar but then again... That's just me.
I did notice that you implemented coyote time and wall grab time but again, way too fast for me to use efficiently. Some of the jumps were just flat out impossible without a lot of practice. I get the use of a button for wall grabbing but it felt like it was on the way rather than supporting the game. Perhaps grabbing the wall automatically would help.
Very nice music and good SFX! The soundscape fitted the game perfectly and complemented it.
Great touch with the stretching and squashing animations. That's some good polishing there.