Separate a missing mod interface from a failed connection. A game that still shows only its normal menu needs an installation check before you diagnose a Steam lobby.
No multiplayer controls
Check that the mod targets your actual full-game or demo build. Verify BepInEx architecture, the installed package version and whether the archive’s mod contents went directly into the correct game root.
The v5.5.0 full-game update does not make an older demo package compatible. Its versioned notes take precedence over advice written before release.
Lobby or start failure
The README specifically recommends launching through the Steam Library if Steam Lobbies do not work. For v5.5.0, all participants must select a character and hit Ready Up before the game starts; late joiners select before loading.
Compare exact versions and reproduce with the smallest matching mod set. This is a diagnostic recommendation, not proof that every failure is a version mismatch.
A session loads but behaves incorrectly
Check the selected release’s known issues. The author flags unreliable crystal-effect synchronization in Crystalline Hollow in v5.5.0. Report the exact layer, event and versions instead of assuming every state mismatch is a vanilla bug.
Do not repeatedly overwrite a valuable save while testing. See installation and mod recovery for the two earlier branches.
Sources & version notes
Reviewed against the primary sources below. Version-dependent details are identified in the article; these procedures have not been personally playtested.
- Casualties Together author installation and features (2026-11-11 checked)
- Casualties Together versioned releases, including v5.5.0 (2026-11-10 / checked 2026-11-11)
Compiled from public sources. We have not personally played or tested these procedures. Check your installed build and its tooltips when details differ.