Music is so good I love how the gun fire goes right along with it. It might be nice to line it up automatically so you're always firing on the beat. Nice sprites and vibe this is awesome. I also got pushed out of bounds but I saw you're already aware of that bug.
A minor different bug I noticed was continuing to shoot the same enemy as they're in their death animation repeatedly triggers the death animation until you stop shooting them.
Very cool stuff thanks for sharing!! Vibrant take on pixel art and 2D aesthetic. Well done!!