New Bungie job posts have offered a glimpse at what the studio may be making next.
Of several vacancies, a player investment designer catches the eye most.
"Do you dream about creating worlds imbued with real value and consequence? Can you find the fine line between a reward that encourages players to have fun and an incentive that enslaves them? Can you devise a way for a player to grow while preserving the delicate balance of an action game?" asked the job advert.
"A Player Investment Designer develops a robust and rewarding investment path, supported by consistent, rich and secure incentives that drives player behaviour toward having fun and investing in their characters, and then validates those systems through intense simulation, testing and iteration."
"If you accept our challenge, you will be responsible for design and implementation of multiple large, awesomely innovative features," added the senior server programmer vacancy.
Bungie's Brian Jarrard, who spoke to Eurogamer following the Activision announcement, was cagey about whether the game might be an MMO.
"I can't get into specifics, but we're definitely looking at building a universe that people want to spend time in," he said. "Much like Halo but we have much more grandiose vision here, so it's a long-term partnership for us.
"We're really embarking on something that will be a significant undertaking for the studio that will involve multiple games set inside this brand new IP and universe."
Activision and Bungie announced a 10-year publishing partnership last week. For now, however, Bungie is focusing on Halo: Reach.