343 Reveals Halo Infinite's Co-Op Beta Launch Date And Details How Cooperative Play Works

gameinformer.com:

Aspreviously promised, Halo Infinite’s long-awaited campaign co-op takes its first steps towards launch, thanks to a network beta flight scheduled for next week. 

Much like the multiplayer beta that proceeded Infinite’s launch last fall, this co-op beta, which runs July 11 to July 22, allows registered players to tackle the entire campaign alongside a buddy to ensure everything works as planned for the full rollout. Because this is a new campaign build that players must download, 343 states that no previous story progress carries over, so players will be starting from scratch. Progress made during the beta will also not transfer back to the retail version. 

In a Halo Waypoint blog post, 343 lead software engineer Isaac Bender and lead world designer John Mulkey discussed the co-op mode’s features. A fireteam of four players can create separate campaign saves for co-op, and progress – such as completed missions, acquired collectibles, equipment, upgrades, and achievements – count toward both players’ individual saves. That means you don’t need to be the Fireteam leader to retain your team’s accomplishments. For upgrade cores, if one player collects one, then the entire team gets it. However, players spend cores individually. 

In terms of how the game accounts for each players' individual campaign progress, Mulkey states:

«The way we are handling this is through something we internally refer to as “No Spartan Left Behind”. When players join the Fireteam and choose their save slots to play on, the game aggregates the states of all missions across those saves and sets up a world state in which any missions completed by all Fireteam members are marked as complete while any missions not completed by all are marked as