Blundell started on the series as a producer for Call of Duty 3, but he’s best known for managing its long-running zombies mode. He headed up both the undead mode and the main story for Black Ops 3, and focused on zombies for Black Ops 4. There’s little doubt that he played an influential role in the Call of Duty series when he took his co-head role in 2016.

His exit comes at a less-than-ideal time for the first-person shooter franchise. Treyarch is believed to be working on Black Ops 5 for this year following turmoil at Raven and Sledgehammer, who were reportedly set to release a Call of Duty game this year but were demoted to support duties after rivalries and departures caused chaos. If so, Blundell’s departure will throw more uncertainty into the mix. While Treyarch may still be in good hands, it probably didn’t want to lose leadership at a moment like this.

According to Activision, Apocalypse Z will introduce several new maps and game modes that will feature zombie content. While details on the new modes are a bit sparse, we know that there will be a continuation of the classic Zombies story called “Alpha Omega” and it will allow players to jump in as both the Primis and Ultimis characters for the first time. Gamers will get their hands on new weapons and will be able to operate the combat robot Reaper. The game’s Blackout battle royale-style map will also get a zombie-themed overhaul.

While Apocalypse Z should keep gamers killing zombies for quite some time, it’s worth noting that some of the multiplayer maps — including the latest addition to the Zombies storyline — requires Black Ops Pass. While the pass was available with some versions of Call of Duty: Black Ops 4, gamers can pick one up for an additional $50 from most major retailers.