Halo could have been handed over to the Call of Duty developers. According to Rebs Gaming, Microsoft considered collaborating with Activision and Sledgehammer Games to create a multiplayer game in the Halo universe.
An early prototype of the project allegedly appeared in June. At this stage, developers were testing basic elements, including character movement. The game was reportedly canceled in early July. However, negotiations between the companies may not have completely ceased.
Microsoft may still be considering Activision's involvement in future games in the series, although no such project has yet been approved. Separately, the development of the online Project Ecker continues, but its connection to Sledgehammer Games has not yet been confirmed.
All information is based on unofficial sources. The possible involvement of the Call of Duty creators shows how much Microsoft is changing its approach to developing its main series.