When Call of Duty: World At War released with a last-minute hidden cooperative mode called Nazi Zombies, no one expected that it would become the behemoth mode it’s known as today. The Zombies game mode became a staple in not only the Black Ops series but for Call of Duty as a whole. Until the release of Call of Duty: Modern Warfare where Infinity Ward decided to opt-out of the Zombies craze and replace the mode with another old favorite, Spec Ops.

According to a new leak, it looks like there might be more to Call of Duty: Modern Warfare than just Campaign, Multiplayer, and Spec Ops. It’s long been rumored that Modern Warfare would be getting its own CoD Battle Royale mode post-launch and now if a new leak is to be believed, it looks like not only are Zombies returning but they might be coming to Call of Duty: Modern Warfare in a new and exciting way.

Recently, a dataminer known as That1MiningGuy, accessed the PC files of Call of Duty: Modern Warfare where they were able to locate a particular file that made mention of the long-running Call of Duty (and pop-culture for that matter) enemies. Dataminer That1MiningGuy found a file called PRESENCE/MP_ZOMBIES hidden among a list of other maps. In a since-deleted tweet, they clarified that files were split into two different files types called CP_maps and MP_maps, which was believed to be a distinction between multiplayer and the cooperative mode, Spec Ops.

Call of Duty: Modern Warfare developer, Infinity Ward previously commented on the reason for the removal of a Zombies mode, stating that zombies would compromise the vision for the game. In an interview with PlayStation LifeStyle, campaign director at Infinity Ward, Jacob Minkof stated: “[…] we’re trying to create an authentic, realistic feeling world. We don’t have the flexibility to do something like put zombies in the game. That would compromise the feeling of playing in a world that feels realistic and authentic and relative to today’s conflicts and things we face.”

Based on the little amount of information revealed in the leak, it’s unlikely that a full-scale Zombies cooperative mode will ever make an appearance in Call of Duty: Modern Warfare. However, that doesn’t limit the presence of the undead in one of the game’s other modes. Back in Call of Duty: Black Ops 4, the Zombies mode was one of three core pillars of the game, receiving three maps at launch, as well as post-launch DLC with new maps, weapons, and playable characters. Treyarch also added zombies as enemies in the Battle Royal mode Blackout, where they would defend powerful weapons and loot in specific locations

The name of the leaked file is PRESENCE/MP_ZOMBIES which clearly indicated that Call of Duty: Modern Warfare is going to feature zombies, that the zombies will purely be a presence in one of the existing game modes rather than getting their own game mode, and that the file is linked directly to multiplayer. The letters MP are written before the word Zombies, something that has been seen many times before in multiplayer map leaks where the file lists the mode, followed by the name of the map.

Most likely, the leak indicates that Infinity Ward is planning to add Zombies into Call of Duty: Modern Warfare in a limited-time multiplayer event that could revolve around the return of an Infection mode, Battle Royale, or even a cooperative mode in Spec Ops. Releasing so close to Halloween ruled out a potential tie-in event, however, other popular online games such as Fortnite, Apex: Legends, Destiny 2, and Overwatch have all featured limited-time events themed around the undead in the past.

Of course, it’s worth mentioning that there is always the possibility the file is nothing m0re than leftover code from development and Infinity Ward chose to scrap the game mode or event entirely. Modern Warfare’s multiplayer recently received two brand new CoD maps as part of a new update that brought a long list of changes including nerfs to the 725 Shotgun.

Call of Duty: Modern Warfare is out now for PC, PS4, and Xbox One.