For the first time, Call of Duty will be launching on Blizzard's Battle.net rather than Steam.
The switch-up was announced during last night's Black Ops IIII reveal event, making it the second Activision project to come to Battle.net after Destiny 2.
"Those of us at Blizzard have been friends with Treyarch for many, many years," said Overwatch game director Jeff Kaplan during the announcement livestream.
"When it came to working on Overwatch, we consulted with Treyarch on a number of features...[now] we're going to be able to talk to players across Black Ops 4, into Overwatch, which should be pretty amazing."
Developer Treyarch has also - per rumours - ditched the single player component for Black Ops 4.
"Going back to the very beginning of Black Ops 4 development, we never had set out to make a traditional campaign," co-studio head Dan Bunting told Eurogamer.
"We always started from the place of, we're going to make something different with this game that was going to be inspired by how our community was interacting with Black Ops 3 and the games over the years. We see more and more players spending more time with multiplayer and zombies, not just in the game, but out of the game, streaming and talking about it in forums. It's generated a really huge crowd response. The decision was, we wanted to make a different style of game this time.
"Throughout the course of development we tried a lot of ideas, a lot of things that challenged convention, that might be a different kind of twist on how we might think of a Call of Duty game in the past, or a Black Ops game in the past. As we did that, some things make it, some things don't.
"The game we're representing today really represents the best of the ideas that have run through that gauntlet of game development, which is pretty typical for how we do things."