Casualties Unknown: How to Install Mods

To install mods in Casualties: Unknown, put the BepInEx 5 mod loader into the game’s folder, run the game once so it creates its folders, then drop each mod’s .dll file into BepInEx\plugins. Almost every mod for the game is a BepInEx plugin, so once the loader is in place, adding a new mod usually takes seconds.

Casualties: Unknown has no Steam Workshop and no official mod tools, but it has a busy modding scene that started during the demo, and the biggest mods were updated for the full release within a day of launch. This guide covers the loader setup step by step, Linux and Steam Deck, which popular mods already support version 1.0, and how to turn everything off again.

Does Casualties: Unknown Support Mods?

Not with official tools. The Steam store page lists no Workshop support, and Orsoniks has not released a modding kit. The developer has welcomed mods, though: the September 2026 progress update said of the new prosthetics system, “i assume people will expand upon this system with mods, which will be cool to see”.

The one thing the game officially supports changing is its text. Orsoniks’ itch.io page says language files live in the game’s Data/Lang folder, and the translations are kept in an official GitHub repository.

Everything else runs through BepInEx, a free, open-source loader that injects plugins into Unity games. Mods are hosted on Nexus Mods and on their authors’ GitHub pages.

Step 1: Install BepInEx

1. Go to the BepInEx releases page and download the BepInEx 5 Windows x64 zip (a 5.4.23 build, the version the game’s mods are written for). Do not grab BepInEx 6.
2. In your Steam library, right-click Casualties: Unknown and choose Manage > Browse local files. This opens the folder with CasualtiesUnknown.exe in it.
3. Extract everything in the zip straight into that folder. You should now see a BepInEx folder, winhttp.dll and doorstop_config.ini sitting next to the game’s .exe. If Windows asks, replace the files.
4. Launch the game once, let it reach the main menu, then close it. BepInEx uses that first launch to build its folders.
5. Open the BepInEx folder. If there is a plugins folder inside it, the loader is working.

The most common mistake is extracting into an extra folder, so the files end up one level too deep. BepInEx only works when winhttp.dll sits right beside the game’s .exe.

Step 2: Add Mods

1. Download the mod from its Nexus or GitHub page.
2. Unzip it if it came as a zip.
3. Put the mod’s .dll file (or its folder, if it ships as one) into BepInEx\plugins.
4. Read the mod’s page for requirements. Many content mods need a shared library such as CUCoreLib, which goes into plugins the same way.
5. Launch the game.

A few mods install differently. The co-op mod Casualties Together, for example, has you copy the contents of its mod folder into the game folder itself, not into plugins. Always follow the mod’s own instructions when they differ from the usual steps.

Linux and Steam Deck

Casualties: Unknown is a Windows game, so on Linux and Steam Deck it runs through Proton, and you still use the Windows x64 build of BepInEx.

1. Extract BepInEx into the game folder as above.
2. In Steam, right-click the game, open Properties, and in Launch Options paste: WINEDLLOVERRIDES="winhttp=n,b" %command%
3. Launch the game once, close it, then add mods to BepInEx/plugins. If the plugins folder did not appear, create it yourself.

That launch option tells Proton to load BepInEx’s winhttp.dll instead of its own, which is what makes the loader start.

Popular Mods That Support the Full Release

The full game changed enough that mods built for the demo can break. These were all updated for version 1.0 by November 10, 2026:

QoL Unknown’s v1.1.1 notes even removed two of its own features, attack assist and the sound cannon indicator, because the 1.0 update added them to the base game. Our guide to whether the game has multiplayer covers the co-op mod and its setup in detail.

Before you install a mod, check its page for the game version it targets. Some list the demo’s version number, and CUCoreLib’s notes say v1.1 is the last release that promises demo support, so newer mods may only work on the full game.

How to Disable or Uninstall Mods

• Turn one mod off: move its .dll out of BepInEx\plugins.
• Turn all mods off for a while: rename winhttp.dll in the game folder (to winhttp.dll.off, for example). The game then starts without BepInEx. Rename it back to switch mods on again.
• Remove everything: delete the BepInEx folder, winhttp.dll and doorstop_config.ini, then use Properties > Installed Files > Verify integrity of game files in Steam.

Back up your save before you add or remove mods, because some mods store their own data in it. Our guide to saving in Casualties: Unknown shows where the save folder is.

Frequently Asked Questions

Does Casualties: Unknown have Steam Workshop? No. Mods come from Nexus Mods and their authors’ GitHub pages, and you install them by hand with BepInEx.

Which version of BepInEx does Casualties: Unknown use? BepInEx 5, the Windows x64 build from the 5.4.23 releases. The game’s mods are not written for BepInEx 6.

Do mods work in the free demo? Many were made for the demo and still list it, but the demo will not get further updates, and newer mod releases are moving to the full game. Check each mod’s page.

Do mods disable achievements? The game does not say mods do. The 1.0 patch notes only say certain console commands now disable achievements outside the sandbox, and some mods add console commands of their own.

Why are my mods not loading? Check that winhttp.dll sits right next to CasualtiesUnknown.exe, that the mod’s .dll is inside BepInEx\plugins, and that any library the mod needs, such as CUCoreLib, is installed too.