Survive the night fighting off zombies from your barricade. Survive longer than a day by making use of the daylight hours effectively by repairing your barricade, searching for weapons and looking for other survivors to help repair and defend.
You and a handful of others form the Last Line of Defense, pooling your remaining stockpile of weapons, special ammo, bunker defenses, and super-weapons to fend off the onslaught by virus infected, bloodthirsty Ravagers.