Killing Floor UnrealScript Modding Setup
This page is a starting point for making KF1 mutators and UnrealScript packages. It assumes you can work with folders, file extensions, binaries, and game directories.
Essential Tool
The main tool is Killing Floor SDK, available through Steam tools:
steam://run/1260/It includes the editor, game script files, and UCC.exe.
Optional Tools
| Category | Tool | Use |
|---|---|---|
| Complete script files | KF1 UnrealScript files | Fill gaps in the SDK when you need a more complete class tree. |
| Binary inspection | UE Explorer | Open .u packages, inspect classes, and view decompiled output. |
| Dependency graph | UnCodex | Quickly inspect package dependencies and class relationships. |
| Redirect files | KFRedirectTool | Build .uz2 redirect files for admins and client downloads. |
| Cache extraction | KF Cache Extractor | Pull packages from the local cache for inspection or recovery. |
| Profiling | ueScriptProfiler.exe | Analyze script bottlenecks from profiler output. |
Minimal Compile Script
A small batch script usually does four things:
del MYMUTATOR.u
UCC make
del steam_appid.txt
pauseDelete the old package before compiling, because the compiler may skip work if the previous .u still exists. Delete steam_appid.txt afterward; leaving it in place can prevent joining servers.
Automation
If you build often, automate the boring parts:
| Tool | Role |
|---|---|
| KFCompileTool | Python-based compile helper with output folders, redirects, and flexible project layout. |
| KFCmdlet | Older batch and PowerShell script collection that can still inspire custom workflows. |
Editors
You can edit UnrealScript with any text editor, but language support helps.
| Editor | Notes |
|---|---|
| VSCode + UnrealScript extension | Most feature-rich modern option. |
| Sublime Text + UnrealScriptIDE | Lightweight alternative. |
| Notepad++ with UDL | Simple fallback if you prefer manual syntax highlighting. |
Setup Checklist
- Install KF1 SDK.
- Create a clean test copy of the game if possible.
- Put your package files under the expected
Systemand class folders. - Create a compile script.
- Compile with
UCC make. - Test in solo first.
- Package server/client files and redirect files only after local testing.