The idea is fun, the music is nice and tense, the name of the game is funny, but with no way to refill your ammo there's really nothing to do but to run away from slimes.

It had potential but without a way to regenerate mana there's no game here. 

The game has good concepts and visuals yet I can't find a way to refill my ammo after I run out the first time.

The game has a good idea and concept but there's nothing to do. As soon as I run out of ammo then the game is just ended I just run around trying to find stuff that's not there

So i find the game needs more mechanic to feel more easily hooked at the start. I also suggest displaying enemies' health so players know how much damage they dealt.