User Summary Zombies returns as the cooperative multiplayer mode for Black Ops 4. The game mode features a wider range of customization, allowing for more personalized play styles. Mechanics of the game can be customized via "Custom Mutations", which include over 100 variables, such as overall difficulty, zombie speed, health, damage, and more. Time-limited events known as "Callings" are also promised to be included in the game for long-term engagement.