Really well done!
Fluid controls, sound is great, art is wonderful, I got a real Zombies Ate My Neighbors vibe! Shotgun and sub-machine gun were just about perfect, the pistol was pretty weak though. IMO it should either fire faster like a semi-auto, or do more damage like a revolver. But that's minor, obviously meant to be the weakest gun for if you run out of ammo.
I'd definitely be interested if you develop this further.