Co-op for two - host a build for friends or in public from the title's Co-op screen, or join one from the list

Joining friends - friends can join your build from the s&box friends list, and picking 2 players at Play hosts one for you

Shared build - one arena, one set of patch notes and commits, level-ups take turns

Revive - stand next to a downed partner to restart their process, shipping the wave brings everyone back

Tuned for two - more and tougher enemies, bosses with extra health

Rewards - both players earn half the team score as career XP, and team achievements unlock for both

Connection - your partner's ping on the HUD, and a warning when the connection drops

Remove - the host can remove a partner from a public build