What's hard about ducking the entire time and shooting. What's hard about keeping your laser cannon they GIVE YOU the room before the zombi room. If you suck at this game, hate yourself, not the game.
with your beginning gun, all it takes is 3 shots in the head, and the gun comes back down quick enough to kill them far away, unless you're stupid and sit there and do absolutely nothing. The machine guns you can just angle so you keep firing with the gun recoiled back as far as possible, the game is really not hard.