Just four months after the release of Marathon, game director Joe Ziegler has announced that he’s leaving the game, and Bungie, effective today. His role will be filled by Del Chafe III, previously the assistant game director, who along with creative director Julia Nardin will “guide Marathon into the next chapter with an even better and brighter future.”

“As for me, I’ll be heading to something new, somewhere else, and will update you on where and what soon,” Ziegler wrote on X. “I just want to say a deeply heartfelt thank you to all of you for supporting me and Marathon in our windy mission to bring a dark and terrifying space survival frontier to your screen.

“The mission will continue in new and surprising ways so stay tuned for what this team has in store for you! It’s been a pleasure seeing all the stories you’ve created, all the clever ways you’ve found ways to murder robots and one another. Hopefully as I move onto new things, you’ll join me for those adventures as well.”

Ziegler’s departure, coming so soon after Marathon’s release and while it’s still struggling to find its footing, is a shock. Bungie is rolling out big changes to Marathon, including an embrace of PvE gameplay in the upcoming Vault Breaker mode, which will debut—temporarily—next week and then roll out in full sometime in season 3.

It’s the worst possible time for instability at the top, in other words, particularly given that a turnaround for Marathon is essential. It isn’t a Concord-esque disaster, but Marathon’s concurrent player counts on Steam are nowhere near what Destiny 2 was (or is even currently) putting up, even when it was in its deepest doldrums.

With the studio gutted and no other releases imminent, Marathon is an existential game for Bungie. Even just as a matter of public perception, losing Ziegler—a highly-regarded developer who only joined Bungie in 2022 and took the reins on Marathon just two years ago—is a major blow: The more it looks like you’re in a spiral, the tougher it is to pull out of it.

Compounding Bungie’s troubles, Ziegler isn’t the only high-profile Bungie employee to leave in recent weeks: Former Marathon design lead Lars Bakken, a storied Bungie developer in his own right, left in June after more than 20 years at the studio and is now “retired from the videogame industry.”