I thought it was a really fun experience!
As far as the mechanics are concerned, it kinda depends on what sort of game you wanted to make. Being able to be damaged by your own bullets is fine, but it meant that the optimal gameplay is to play really cowardly.
Like, at the gates, there are little red arrows showing you where the enemies are, which means for one of the levels i just used the shotgun down a nearby hallway, then backed away & waited for a screen shake. And repeated until all the enemies in that direction were gone. I don't think I would have done that if I was immune to my own bullets.
One mechanic I really didn't like, though - I thought it was lame how my bullets bounced off the enemies. Like if an enemy is right in my face, I shouldn't be forced to choose damage from the enemy or damage from my bullets.
I really love the sketchy artstyle! Maybe in a future version, the "world" could be fleshed out a bit more? Like yes, bat with a gun, love it, but why am I going through these cybergates? Are the circle guys the natural predators of gunbats?