Casualties: Unknown Co-op Support and Mod Versions

There is no built-in co-op

The official Steam listing identifies Casualties: Unknown as single-player. Casualties Together supplies a separate community co-op mode with Steam lobbies. Install it on each participant's game rather than expecting an unmodified copy to join. Sources: Steam, the mod author's README and the setup guide.

Version status for 1.0

Choose the full-game package before following installation steps. The author's v5.5.0 release explicitly targets Casualties: Unknown v1.0 and warns that testing is incomplete. The archived setup guide identifies the package as MPMod_5.5.0_fullgame1.0_bepinex5.4.23.5.zip. See the author's release notes and package comparison.

The author's v5.4.0 notes also describe its full-game port as unfinished. Do not select that older port merely because an old video uses it. The table identifies archived packages, not a claim about the latest demo release.

How the mod connects players

First complete the mod installation steps. Casualties Together uses the complete contents of its archive's mod folder in the game root, preserving the supplied layout. Launch through Steam and check that multiplayer controls appear in the main menu. These checks come from the author's installation instructions.

What happens when the host starts?

Use the installed mod's multiplayer menu and its current setup guide for the exact lobby controls. This reference confirms Steam-lobby support from the author README; it does not independently verify every control in that third-party walkthrough.

For v5.5.0, the author specifies this readiness sequence: when the host starts, participants choose a character and press Ready Up. Gameplay starts when everyone is ready. Late joiners also select a character before loading in. The v5.5.0 release notes and setup guide document character readiness. Do not confuse starting this readiness flow with immediately spawning everyone into the run.

Limits and troubleshooting

These checks come from the setup guide and README. No live lobby test or compatibility test beyond the author's v1.0 target is claimed. The v5.5.0 limited-testing warning remains relevant even after a successful connection.