Play co-op with friends and troubleshoot invites

1. Use Steam on Windows, macOS or Linux; Mega Crit also lists Steam Deck compatibility.
2. Have the group ready on Steam friends before starting multiplayer.
3. Use the game’s multiplayer lobby and invite controls.

   Older footage · checked Oct 13, 2026 · before Early Access updates after March 2026 (Main 0.107.1)

   0:19–0:52 · 33 sMain menu Multiplayer, Host or Join, then the lobby’s invite button

   0:19–0:52Main menu Multiplayer, Host or Join, then the lobby’s invite button
4. Compare game versions if one player cannot join. Keep everyone on the same Main or Beta branch for a controlled troubleshooting attempt.

Co-op turns are simultaneous: you can play cards during your turn without waiting for another player to act. That makes communication useful when several plays could change the same fight.

Edward Lu’s April 19, 2026 account says some actions can affect teammates. Examples include cards that give another player energy or make them draw cards, so call out support plays before committing them.

The party travels together, rather than occupying different rooms. Outside combat, players usually make unrelated choices, though Lu notes exceptions; this does not establish that every reward or resource choice is shared.

This is attribution to Lu’s April 19, 2026 implementation account, not a current Main or Beta playtest.

The reported co-op answer is no: one player’s Claw plays do not raise a teammate’s Claw damage, even though the card says all Claw cards. Build and count Claw scaling separately for each Defect.

Cruelty is also reported as owner-scoped. Its extra damage against Vulnerable enemies applies to attacks made by the Ironclad who played Cruelty, rather than increasing every teammate’s damage.

These conclusions come from an August 31 player report and the community wiki’s multiplayer notes. Neither source identifies an official rule statement, and Kingy has not reproduced the interactions in a named Main or Beta build. Recheck after a patch and record the branch if your group sees different behavior.

Check whether Steam and its overlay are available. The v0.111.0 beta specifically adds an error when using Invite with the overlay disabled. Do not assume that beta behavior is present on Main.

For a repeatable failure, record branch, version, party size and the exact error. For modded co-op, compare the enabled mods as well as the game branch. Mega Crit recommends matching the exact mod set, especially gameplay mods. Switching to unmodded mode uses separate progress; read the patch guide’s save section before treating an empty profile as lost data.

Co-op has multiplayer-specific cards and team synergies. Announce which enemy you intend to finish and when you need support. Re-read the remaining intents after another player changes the fight. Solo enemy values are not a reliable party-size table.