Certain Affinity have been working on Halo and Call of Duty franchises since 2007, providing support for many projects. During early 2022, they announced that they now had additional duties for the development of Halo Infinite.
Currently, this unannounced Halo Infinite project is the largest current active project at the company. CEO Max Hoberman says that they have been working on this project for over two years now, and they are still not allowed to tell anything specific about it. We only know that it is big, and it is new. Anything further is only up to guesses.
Almost 100 developers are working on this project and apparently it will take some more time to complete it. Back in January, there were rumors about a possible new game mode for Halo Infinite. Most notable guess about a new game mode was Battle Royale, but it could be a total surprise too. We will have to wait and see when Certain Affinity is allowed to speak about it more explicitly.