Loved the aesthetic.
Some of the mechanics felt like they were working against each other. such as the recoil when you fired and the bullets being kind of far away when you shot made it so it was difficult to set up jumps, often recoiling into the spikes right behind you. Then also bouncing off of a bullet when you land on it made it so you had to spam jump to do what you wanted to.
I also got a little confused when i first got the gun because the breakable blocks weren't too clear, and felt like i was supposed to go backwards, but that's possibly just unlucky as it wasn't my first reaction to just fire the gun randomly (partially because i had to go look up what button fired it). Possibly having space behind the blocks in that room open instead of just fully filled in with the breakable blocks would help, or possibly something to pick up on the other side it would entice the player to shoot it