This variable affects the number of zombies that spawn.
- Peaceful: Hardly any zombies spawn. You can run around and still not find many zed.
- Overrun: Nearly impossible not to find any area overrun by zombies. Lag will be as lethal as the dead here. Be prepared, and think fast.
- Weak: Killed in one hit from most weapons, and must swarm the player to kill them. Most bosses are very weak.
- Normal: Zombies die from a low volume of bullets, akin to many arcade games.
- Stronger: Zombies have a realistic amount of health, and have a similar damage model to living humans. Upgraded bosses.
- Unstoppable: Very strong, and will occasionally kill the player in one hit. Zombies have tons of health, and all bosses are extremely powerful.
- Lots: Loot is plentiful, and will often provide uncommon weapons, equipment, and armour.
- Some: Loot appears at a medium frequency, but will no longer give powerful weapons.
- Miniscule: The only things loot will ever give are ammo and parts; however, parts are much more likely to be for a powerful buildable.
- Strong: Many allies, and all have plenty of health.
- Some: A smaller number of allies to support you, and they aren't strong compared to last time.
- Few: You are vastly outnumbered. Make your few men count, and protect them well.
- None: You are on your own.
- Casual: Zombies cannot sprint, and are weaker than normal. Suppression isn't dealt to you.
- Deathwish: Any damage at all kills you. Good luck.
- Chaos: Gameplay is massively sped up.
- Indestructable: Zombies cannot be killed by any means, and all weapons grant zero stopping power against them.
- Nightmare: Zombies are extremely aggressive.