How to install Casualties Unknown mods

Almost every mod for the game loads through BepInEx, a plugin loader for Unity games. Once it works, adding more mods takes seconds.

How do you install BepInEx for Casualties Unknown?

The steps below come from the Steam community modding guide. confirmed

Windows

1. Download BepInEx 5 for Windows x64. The guide links version 5.4.23.4, and the popular co-op mod links 5.4.23.5. Use whichever your mod asks for.
2. In Steam, right-click the game, then Manage > Browse local files. The default path is under steamapps\common\.
3. Extract the zip straight into that folder. Accept “Replace all files” if asked.
4. Run the game once so it generates its folders, then close it.
5. If a BepInEx/plugins folder now exists, it worked.

Linux and Steam Deck

Use the Windows x64 zip of BepInEx here too, because the game runs through Proton. confirmed

1. Extract it into the game folder.
2. In Steam, open the game’s Properties, and under General > Launch Options paste WINEDLLOVERRIDES="winhttp=n,b" %command%.
3. Run the game once, then close it. If plugins did not appear, create it inside BepInEx.

On a Steam Deck, do all of this in Desktop Mode. Players on the forum say it works the same way as any other Linux install, and that no mod manager supported the game on Linux at that time. reported

macOS

The guide’s author only got this working through CrossOver, by opening the whole folder in it, installing Arial fonts through CrossOver’s store if needed, and adding winhttp.dll as a DLL override in the Wine configuration. unverified Steam lists Windows 10 as the only supported system, so expect rough edges.

Where do Casualties Unknown mods go?

Most mods are a single .dll or a zip containing one. Extract it and place the files here: confirmed

<game folder>/BepInEx/plugins/

Some mods differ, and the mod’s own page always wins. The co-op mod copies into the game root, and skin mods add a CustomSprites folder. Check the mod page for required libraries too. CUCoreLib, for example, is a dependency of many mods and has 36,038 downloads for that reason. confirmed

Why is my mod not working?

The community guide lists four checks, in this order. confirmed

Check	What to look for
BepInEx location	Beside the game’s .exe, not inside a nested folder like BepInEx_win_x64_5.4/
Mod location	The .dll is in BepInEx/plugins
Dependencies and version	The mod page’s requirements match your game build
The mod’s own steps	Some mods need extra files or config

Two more causes are worth checking on your own:

• Wrong game build. Mods were written for the demo, and the full game launched on 9 November 2026 with a large set of changes. The developer also said the demo would not receive those changes, so a mod for one may not load on the other.
• Two mods doing the same job. Installing two skin changers or two libraries of the same kind is a common source of conflicts. Remove half your mods, test, and narrow it down.

Do you need a mod manager?

Not for a handful of mods. A manager helps when you want to switch sets of mods on and off without moving files. confirmed

Manager	What it adds	Downloads on 9 Nov
Alexx_’s Mod Manager	A Mods tab in the settings menu that toggles BepInEx plugins	7,477
Mod Manager by Foxiecub	Toggles by renaming files to .dll.disabled, with presets	2,021

Both are in-game toggles, so they still need BepInEx installed first.

Is there Steam Workshop support for Casualties Unknown?

No. Steam lists no Workshop for the game, and players on the forum have asked for it. reported Mods are distributed through Nexus Mods, GitHub and the modding Discord. Nexus had 544 mods listed for the game on 9 November 2026. confirmed

Once your loader works, the best mods list is the next stop, and console commands work without any mod at all.

How do you remove mods?

Delete the mod’s .dll from BepInEx/plugins. To remove modding entirely, delete the BepInEx folder and the winhttp.dll and doorstop_config.ini files that came with it, or use Steam’s Verify integrity of game files, which restores anything the mods changed. Back up your saves first if you want to keep a modded run.