My hard drive made funny sounds while playing this 😀, could just be a Unity quirk. Although, your game does run very smoothly and the visuals are right up my alley. It's a bit difficult figuring out where I should go so more direction would help. Would love to see more of this game if you continue developing it.
I'd suggest changing the aim so that it just shoots in the direction of the mouse, but flat with the ground and not directly at the mouse position. If I'm standing under something or click on a wall, the bullet will go straight up or towards the camera.