In the side-game, "Nazi Zombies!" on the map Nacht der Untoten, open the Help room (the one that says "Help" on it) during the 3rd or 4th round. It will supply weapons that will give you the upper hand in a crucial battle. But beware: there are 4 openings that the zombies will try to break through. Also, NEVER open up the stairs; it just means more zombies. If you want weapons, go to the Help room.