Awesome game with really interesting puzzles. I love the theater aesthetic, and the hand drawn art is beautiful! There were two main things I had difficulty with:
1. I made the incorrect assumption that you could only press up to "jump" when you're on the ground. This lead to me getting stuck on the level below for a while until I realised you could spam the up button.
2. As 497f pointed out, the inconsistency with how pressing 'E' worked was confusing. Sometimes it affected the other Muskoom globally, sometimes within a range, and for another level it didn't seem to do anything until after you bumped into another Muskoom.
The use of the vine platforms with a wavy collider was cool, it made for some more unique physics interactions. It felt nice being able to help all the Muskrooms get to the exit. Great work!