The multiplayer project’s Linux instruction is a Proton launch option: WINEDLLOVERRIDES="winhttp=n,b" %command%. The author says this tells Proton to load BepInEx. It is not a Steam Deck performance certification.
Match the Windows mod environment
The README’s loader prerequisite is Windows x64 BepInEx. Check the intended game build and selected mod release before applying an override; a Linux device does not make a demo-only package compatible with full game 1.0.
Open the intended Steam entry’s local files and confirm the loader and mod contents are in that game root. A separate demo entry has a separate directory.
Add the documented option
Preserve any existing launch options before editing. Add the author’s override through that Steam entry’s properties, then launch from the Library and check for the expected multiplayer buttons.
If the interface does not appear, return to version and folder-layout checks. Repeatedly adding the same launch string does not fix a misplaced plugin.
Limits of this guide
We have not measured Steam Deck framerate, controller usability or battery life, and the official store snapshot lists Windows requirements. This page documents the mod author’s Linux loading instruction only. Use installation and troubleshooting for the next diagnosis.
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)
- Official Steam store: Casualties: Unknown (2026-11-11 checked)
Compiled from public sources. We have not personally played or tested these procedures. Check your installed build and its tooltips when details differ.