How to install mods in Casualties: Unknown with BepInEx, where the mods live, how to fix a broken install and which mods are worth using.
Casualties: Unknown Mods: BepInEx Setup and Best Mods
Casualties: Unknown has no Steam Workshop. The mod scene runs on BepInEx, the same loader used by most Unity survival games, and the mods themselves live on Nexus Mods under the game's original name, Scav Prototype.
That naming split is the first thing to understand: the Nexus page still uses the prototype name, the game uses the release name, and the loader does not care what the folder is called.
Official source: Casualties: Unknown on Steam ↗
What you need
- The game, installed and launched once.
- BepInEx 5 LTS, currently 5.4.23.5 for this game.
- The mod's
.dllfile and any dependencies listed on its Nexus page. - A way to unzip files.
BepInEx 5, not 6. The 6.x line targets a different Unity runtime and most Casualties: Unknown mods are built against 5 LTS. Installing the wrong major version is the most common reason "mods do nothing".
Installing BepInEx
- Download the BepInEx 5 LTS x64 build.
- Extract the contents into the game's install folder — the folder that contains
Casualties Unknown.exe. - Launch the game once, then close it.
- Check that a
BepInExfolder now exists next to the executable. - Put mod
.dllfiles inBepInEx/plugins. - Launch again and check the BepInEx console for the mod's load line.
The first launch generates the config files. Do not create them by hand.
Installing a mod
- Read the mod page's requirements. Some mods need a shared library, a config framework or a specific BepInEx version.
- Copy the
.dll(and any folder it ships with) intoBepInEx/plugins. - Launch the game.
- Check the console for errors. A mod that fails to load usually prints an exception with its assembly name.
- Test in a throwaway run before installing ten mods at once.
Install one mod at a time. When something breaks, the last mod you added is the cause.
The current mod list
Nexus lists 536 mods for the game. Most are small quality-of-life changes, item tweaks or custom structures. Three are worth knowing by name:
- CU-Custom-Structures — adds custom structure generation, the closest thing to player-built content in the current scene.
- QoL Unknown — a bundle of quality-of-life changes: UI, inventory and interaction tweaks.
- TarkovMedicalMod — expands the medical system with additional items and treatments.
The best mods guide covers what each one changes and who should install it.
Demo vs full release
Mods built for the demo may work in the full release, but there is no guarantee. The full game adds six layers, new items and new systems; a mod that patches a demo-only function will fail to load or, worse, load and corrupt state.
Before 9 November:
- Test mods in the demo.
- Keep a clean, unmodded install for the first full-release run.
- Check the mod's "last updated" date after release.
After a game patch, assume mods are broken until the author updates. BepInEx itself rarely breaks; the mods do.
Common problems
The console does not appear.
BepInEx did not install correctly. Check that winhttp.dll and the doorstop_config.ini are in the game folder, not in a subfolder.
The mod loads but nothing changes. The mod may depend on a config file, a keybind or a specific game version. Read the mod page's installation notes.
The game crashes on launch. Remove the last mod you installed. If it still crashes, remove all plugins and re-add them one at a time.
The game crashes on layer load. Custom structure mods are the usual suspect. Disable them and test the same layer.
Steam verifies files and deletes BepInEx. Steam does not delete unknown files, but a "verify integrity" can restore overwritten assemblies. Reinstall BepInEx after verifying.
Uninstalling
- Delete the mod
.dllfromBepInEx/plugins. - Delete its config file from
BepInEx/configif you want a clean reset. - To remove BepInEx entirely, delete
BepInEx,winhttp.dll,doorstop_config.iniand.doorstop_version.
Your save files are separate. Back them up before a big mod change.
Is modding safe?
BepInEx mods run arbitrary code. Download only from Nexus or the mod's official repository, and check the author's other work. A mod that asks you to disable your antivirus is not a mod you should install.
Mods do not affect Steam achievements because the game has none. They can affect saves, especially mods that add items or structures: a save created with a mod may not load without it.
Should you mod the first run?
No. Play the first run unmodded. The game's balance assumes the vanilla item pool, and the medical system is the point of the game. Add quality-of-life mods after you have seen the first five layers.
The exception is a accessibility or UI mod that makes the game readable on your setup. That is a personal call, not a balance change.
Most mods target BepInEx 5 LTS. Installing 6.x is the most common reason a mod silently does nothing.
FAQ
Does the game support Steam Workshop? No. Mods are manual, through BepInEx and Nexus.
Which BepInEx version? BepInEx 5 LTS 5.4.23.5.
Do mods work in the demo? Many do, but they may break in the full release.
Can mods break saves? Yes, especially item and structure mods. Back up saves before installing.
Is there a mod manager? Not officially. Install manually or use a generic BepInEx mod manager at your own risk.
Where do mods go?
BepInEx/plugins.
Sources and further reading
Related guides
More Casualties: Unknown Guides
Every weapon in the Casualties: Unknown demo ranked: damage, swing speed, durability, ammo and which weapon fits which layer.
How blood volume, bleeding rate, tourniquets and transfusions work in Casualties: Unknown, and the order to treat a bleeding limb.
The three playable characters in Casualties: Unknown, what Experiment can do in the demo, and what is actually confirmed about Milky and Dune.
How crafting works in Casualties: Unknown: the five tabs, Intelligence requirements, failure tiers, blueprints and the recipes worth making first.
What the free Casualties: Unknown demo includes, how long it takes, where it ends, what carries over and how to install it on Steam.
All six Casualties: Unknown presets plus the 41 custom run settings, with defaults, ranges and the options that actually change survival.
Casualties: Unknown endings explained: the confirmed story goal, the unreleased final layers, what the demo does at layer 5, and what is still speculation.
Every enemy in Casualties: Unknown, its layer, attack pattern and drops, plus the Elder Thornback fight and the traps that kill more players than monsters.