No one could have imagined that you’d be able to throw an explosive cymbal-banging monkey toy at a horde of voracious zombies in a franchise popular for it’s brutal, semi-accurate depictions of World War II and other major conflicts. It’s something so wild that it could only be part of Treyarch’s next edition of their zombie mode in ‘Call of Duty: Black Ops 4.”

The Treyarch led zombie mode has come a long way in the last 10 years, many fans pick up each entry in the series for nothing but the newest undead horde mode. The upcoming game, which is hitting most platforms on October 12th, is taking note from everything that has happened since they mixed zombies and war in “Call of Duty: World at War” for the first time.

“We’ve never played it safe when we start out making another one of these,” Treyarch executive producer Jason Blundell tells Variety. “It’s all about the risk, we never want a map that’s universally loved. We think the passion that our fans have for zombies is rooted in how different each experience can be.”

The key change that both Blundell and lead writer Craig Houston emphasized was how the three new maps, Voyage of Despair on the Titanic, IX set sometime in an ancient Rome-like coliseum, and the more typical Blood of the Dead prison, are telling a completely new story, allowing them to ‘reset the rules’ of the gameplay and narrative.

“Each time we start designing one of these maps we treat it like we’re doing it for the first time,” Blundell said. “We don’t want anything to be generalized across modes. The design layout of each map is incredibly different, the Titanic has all sorts of chokepoint hallways while the Coliseum in IX is far more than a typical arena, we’ve shown that in trailers.”

“We’ve never tried to do the same thing twice,” Houston added. “We’re able to tell a story without the baggage of the previous games, we’re not continuing with what happened after Aether.”

There is still a lot of mystery around the details of this new ‘Chaos’ storyline. Different trailers revealed at San Diego Comic-Con show characters wielding strange staffs that appeared to transport them between the different maps, although Blundell told us that it doesn’t work that way in-game.

We do know that the primary character is Scarlett Rhodes, a young woman whose father has disappeared due to some sort of dark magic. Rhodes unites with three friends, Diego, Bruno, and Shaw, to find her lost family member and along the way she uncovers a mysterious artifact that could threaten mankind.

The new storyline, which appears to feature time travel, allowed the team at Treyarch to completely reinvent the systems around their classic horde gameplay. “We wanted to go back to the core of zombie gameplay, which is play it until you die basically,” Houston said. “We’re also poking into mythology which opens up all kinds of opportunities for new systems.”

Blundell explained that they were ditching a lot of the extraneous systems that they’ve built around the core gameplay, and have created new ones that work better with the more contained worlds in “Black Ops 4.” Two of those include custom mutations, which allow the player to adjust hundreds of variables like difficulty and zombie speed in order to make the mode more replayable, as well as factions that the player can join and earn rewards in over time.

Houston and Blundell believe that the zombie mode shares the same mentality that the Black Ops series does. Both the primary campaign and the missions within the horde mode explore an alternative take on history.

“A big core of what the fans love about zombies is how we take things from history and just twist them and build something around that,” Houston said. “The Titanic is a good example, we’re not changing that event and how it actually played out in history.”

The “Black Ops” installments in the “Call of Duty” franchise have focused on unknown missions carried out by special forces across the globe. While a lot of the series is rooted in fiction, they do take place during real-world events like the Cold War between Russia and the United States and the Bay of Pigs invasion on the beaches of Cuba.

“Black Ops is all about the story behind the truth, which tells you about these sacrifices made that were never recorded in history,” Blundell added. “It’s the same idea here, we imagined a zombie world that can sit with the timeline we’re used to. It can sit with the history we learned in our textbooks because it’s happening in places you don’t see and is cleaning itself up afterward.”

Blundell even said that this mentality they’ve used to design the zombies mode was around before “Black Ops” during the development of “Call of Duty: World at War.” Citing how some design elements like heavy metal playing over an orchestra during the invasion of Berlin were a step towards the ‘edginess’ of the “Black Ops” series.

The zombies mode has evolved into a completely different beast since the first entry came out in 2008, moving from being primarily DLC driven to becoming something more fully-fledged. It achieved a lot of firsts for the Call of Duty franchise, setting itself apart from other elements of the series and building a fan base of its own.

“We had no idea since it started as this little easter egg thing, how much zombies was going to take off when we first started,” Houston said. “I think that’s partially due to how we approach it, how we look at every element as a risk.”