I like the idea of "maintaining momentum" in the game, but it didn't seem like it was implemented as well as it could have been.
It was easier to just jump through enemies and abuse i-frames rather than bother with the idea of shooting them. There only was a very small subset of enemies that were necessary to shoot.
There were also several places where it looked like it was possible to jump but it wasn't. The majority of the gameplay revolves around shooting 6 bats.
It took me about 5 minutes to realize that you could use the mouse -- some sort of cursor or visual feeback might be good. Simply having the character hold the gun from the beginning might have also helped.
While it's simple, I really appreciate the sound design just being a simple beat that gets more intense. Pixel art was also very well-rounded.