I love a good beat'em up.
I think you have a solid foundation for the game. Like Burnerknight mentioned before, the game gives you that dopamine hit that keeps calling you to play again.
In terms of improvement, the fighting mechanics need more polishing.
- It suffers from 'ghost' hits, which is when you get hit, but is unclear who or when.
- Speed up the hitting animations (aka Fire Rate), They felt slow.
- Block/Dodge. I missed having a dodge or blocking mechanic in the game. Maybe there's a shield weapon that I didn't get.
- Permanence: keep the bodies in the scene as you defeat them. Same with throw able weapons, weapons, bullet caskets, etc. You can reset them per stage.
- Jumping: the jumping mechanic is useless. There are no obstacles or different floors on the level, and it doesn't save you from getting hit. See my point on Block/Dodge.