There are two factions in Zombie Panic: Source; the living, and the undead. The undead are the re-animated corpses of survivors who have perished during their struggle against the zombie horde, and now hunger for the flesh of their former comrades. Should you find yourself suddenly unable (or lack of need) to breathe, feel pain, or resist eating flesh after a run-in with a zombie, it should become apparent that you have become one. Zombies have one goal; destroying the survivors, which results in the creation of more zombies.