Raven Software were once working on a 'Call of Duty: Zombies' live service game.
The studio's former lead designer Michael Gummelt has revealed the team were previously working on the "ambitious" project, but the game's IP originator - which is believed to be Treyarch - "wanted it back".
An entry on his LinkedIn page reads: “Lead Designer on an ambitious new 'Call of Duty: Zombies' live service project.
"Canceled when the ATVI studio that 'owned' that part of the Call of Duty IP wanted it back.”
Raven also tried to work on a game under their name as they moved away from the 'Call of Duty' franchise.
However, their goals of reviving one of their classic IPs fell through as Activision scrapped the idea in favour of 'Warzone'.
Gummelt added: "Lead developer on a very small incubation team on two highly playable, well-developed prototypes as proof of concept for a revival of a classic Raven IP. As part of the Activision 'Press Start' initiative, which ended soon after 'Warzone' launched and was successful."
Some fans have speculated this classic IP could have been a new 'Hexen' title, although there is no confirmation on the mystery game.
Now, Gummelt himself is working as an "experience director" on a triple-A game for Zenimax Online Studios.