Installing and Configuring KF2 Server Mutators

KF2 Server Mutators

Mutators are server-side game modifiers — they change gameplay rules, add features, or adjust balance without requiring client-side downloads. Common KF2 mutators include custom trader time adjustments, spawn rate modifiers, and additional perks.

Where to Get Mutators

Mutators are distributed as .u (compiled UnrealScript) files. Sources include:

• Steam Workshop — look for items tagged "Mutator"
• KF2 Modding Community — Tripwire Interactive forums

Installing a Mutator (Manual)

Step 1 — Upload the files

Most mutators include a .u file and sometimes a .upk (package) file. Place them in:

KFGame/BrewedPC/

mkdir -p /home/steam/kf2server/KFGame/BrewedPC/
scp MutatorName.u user@YOUR_SERVER_IP:/home/steam/kf2server/KFGame/BrewedPC/

Step 2 — Register the package

In KFGame/Config/LinuxServer-KFEngine.ini, find [UnrealEd.EditorEngine] or [Core.System] and add:

[Core.System]
Paths=../KFGame/BrewedPC/*.u

This line is usually already present — check before adding it twice.

Step 3 — Enable the mutator on launch

Add ServerMutators= to your startup URL:

KF-BioticsLab?game=KFGameContent.KFGameInfo_Survival?ServerMutators=MutatorPackage.MutatorClass

Combining Multiple Mutators

Separate mutator classes with commas — no spaces:

?ServerMutators=Package1.Class1,Package2.Class2,Package3.Class3

Workshop Mutators

If the mutator is available on Steam Workshop, add its ID to LinuxServer-KFGame.ini:

[OnlineSubsystemSteamworks.KFWorkshopSteamworks]
ServerSubscribedWorkshopItems=WorkshopID1
ServerSubscribedWorkshopItems=WorkshopID2

After the server downloads the workshop item, the mutator's class name will be listed in the item's Workshop page description.

Verifying Mutators Are Active

Check the server log (KFGame/Logs/Launch.log) for lines like:

[0000.00] Init: Mutator MutatorPackage.MutatorClass

If you don't see it, the class name may be wrong or the package didn't load. Double-check the exact Package.Class from the mutator's documentation.

Common Issues

Mutator not loading: Make sure Paths= in LinuxServer-KFEngine.ini includes the directory where the .u file was placed.

Server crashes on launch: A mutator compiled for an older KF2 version may be incompatible. Check the mutator's Workshop comments for known issues.

Class not found error in log: The Package.Class in ServerMutators= is case-sensitive. Copy it exactly from the mutator's readme or Workshop description.