Overlies
From this IGN interview with Jeff from The Overwatch Team about Overwatch 2:
It is definitively an online cooperative story experience. That's what we think is cool and unique and innovative about it. You don't traditionally play story or campaign games with other people, and we think that's going to make it feel very distinctly Overwatch or Overwatch 2.
Just off the top of my head, chronologically:
2004: Halo 2
The game's "Campaign" mode offers options for both single-player and cooperative multiplayer participation.
2006: Gears of War
All Gears of War games feature a campaign mode that can be played cooperatively with one other player. The two players take the roles of two COG soldiers, Marcus Fenix and Dominic "Dom" Santiago, as they fight the Locust. In the third game the campaign allows for up to four players to play together at the same time.
2009: Borderlands
The game features the ability to explore the in-game world, and complete both main missions and optional side quests, either in single-player or online cooperative gameplay, with the latter providing additional options for duels and competitive PVP matches in designated areas.
As Reinhardt would say:
YOU SHAME YOURSELF
