Instructions
Maximize your point scoring. The more points you get, the more items you can buy. In the early rounds, hit the zombies with up to six non-lethal pistol shots, by aiming for the body and limbs (10 points each), then finish them off with the knife (130 points). In later rounds, it's better to aim for the head (100 points) so that you have more chance of surviving and progressing to higher rounds.
Collect power-ups. Zombies occasionally drop glowing items when they die within the building you are protecting. These are power-ups which include "Insta-Kill," which makes zombies die after one shot, "Double-Points," "Max-Ammo," "Nuke," which kills all zombies on the map, "Carpenter," which re-boards all windows, "Fire Sale," which reduces the price of the Mystery Box to 10 points, "Random Perk Bottle," which gives a free Perk-a-Cola, and "Death Machine," a powerful mini-gun.
Purchase new weapons. These appear on walls as white outlines of the weapon in question. Walk up to the wall to see the price for the weapon itself, or for just an ammo reload. Press and hold the action button if you want to buy it.
Use the Mystery Box. This appears on every map, costs 900 points and provides a random weapon. This might be one that is not obtainable from the map itself, or it might be a horribly ineffective weapon. This is a gamble but if you have kept your point-scoring high, you'll be able to try this several times.
Buy items from vending machines. These items increase the attributes of your character. "Quick Revive" lets you revive yourself or your team-mates more quickly;"Pack-a-Punch" upgrades your weapon; "Jugger-Nog" makes you more damage-resistant; "Double Tap Root Beer" increases your firing rate, and "Speed Cola" makes your player faster. Perks last until you fall.