I really enjoyed the game, and having no limited ammo and no cooldown made me feel like I was using a machine gun, which was really satisfying and fun. I also really liked the mechanics of the anvils, and how some enemies shoot ice at you, and you have to dodge it, keeping you on the move.
One thing that I would personally change, is to make the game a real time strategy game. By this I mean that the shooting is automatic, but slow, and you can upgrade it as you gain more "resources" (which are dropped by the enemies). You can also upgrade other things like the anvil strength / speed. I think that by slightly changing the game it can be more fun and challenging.
Obviously this is a Game Jam with limited time and this project is still really good, but I'm just throwing out ideas.