Hey! I loved the idea! It reminded me of a super mario world rom hack, in which Luigi has shotgun! I had trouble getting past the room in which you need to fall down, and then shoot midflight to propel you to the left. The momentum of shot was not enough to bump me up. I managed to do it once, but really hard to get there again. I think is important to review how much the shot changes your momentum when falling.
Nevertheless, I enjoyed the art style, the music and the overall idea.
I invite you to play mine if you want :)