Agree with Feras. This is a tank battlefield. LOL. I had fun with this one.
The base concept here has potential. Unfortunately, once I figured out I could endlessly spam left & right click at the same time, and that no collision damage happened if I sat on top of enemies, it was GG. I could kill all enemies faster than they spawned leaving no challenge or replay potential.
Increasing challenges, or levels would be a nice add. Or, limiting the fire rate or quantity of explosive ammo would be another good option. Lots of ways to do it, and you have a good base concept here to work from.