This is amazing, most original idea, most fun gameplay, most polished game overall. and you did this all by yourself. It even has cool story. This is amazing.
now to the nitpicking.
I was stuck for quite some time on the last checkpoint because i did not realize enemies were respawning, so i was trying to clear them before getting to boss
enemy bullets feel very unfair, first they go trough walls (so does players but still, feels unintuitive) second and this is what makes them very hard to avoid, the camera is centered so there is not time to react. it is considered a good practice to move camera ahead in direction of movement to give player reaction time
and game hanged after i tried to start it after beating it.
but that is really nothing compared to how good this is.