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UELib

The Unreal library (UELib) provides you an API to read (parse/deserialize) the contents of Unreal Engine game package files such as .UDK, .UPK. Its main purpose is to decompile the UnrealScript byte-code to its original source-code.

It accomplishes this by reading the necessary Unreal data classes such as:

UObject, UField, UConst, UEnum, UProperty, UStruct, UFunction, UState, UClass,
UTextBuffer, UMetaData, UPackage

Classes such as UStruct, UState, UClass, and UFunction contain the UnrealScript byte-code which we can deserialize in order to re-construct the byte-codes to its original UnrealScript source.

Additionally UELib is also capable of deserializing of many more data classes such as:

UFont, USound, UPalette, UTexture,
UTexture2D, UTexture2DDynamic, UTexture2DComposite, UTexture3D,
UTextureCube, UTextureFlipBook, UTextureMovie
UPrimitive, UPolys

How to use

To use this library you will need .NET Framework 4.8 (The library will move to .NET 6 or higher at version 2.0)

Install using either:

• Package Manager:

    Install-Package Eliot.UELib

• NuGet: https://www.nuget.org/packages/Eliot.UELib

• Usage: See the documentation for more examples.

    using UELib;

    // Instantiates a FileStream and deserializes the package's header, will also auto-detected a suitable build to associate the package with.
    var package = UnrealLoader.LoadPackage(@"C:\Path\Package.upk", System.IO.FileAccess.Read);
    Console.WriteLine($"Version: {package.Summary.Version}");

    // Necessary if working with packages that have been cooked for a console platform, and IF the build was not properly auto-detected.
    // package.CookerPlatform = BuildPlatform.Console;

    // Initializes the registered classes, constructs and deserializes(loads) the package objects.
    package.InitializePackage();

    // Now we can iterate over all the initialized objects, but beware! This includes fake-import objects.
    foreach (var obj in package.Objects)
    {
        // If positive then we have an export, or import if negative, if null, we are working with a 'None' object, but this shouldn't occur here.
        if ((int)obj > 0)
        {
            Console.WriteLine($"Export:");
        }
        else if ((int)obj < 0)
        {
            Console.WriteLine($"Import:");
        }

        Console.WriteLine($"ObjectIndex: {(int)obj}");
        Console.WriteLine($"Name: {obj.Name}");
        Console.WriteLine($"Class: {obj.Class?.Name}");
        Console.WriteLine($"Outer: {obj.Outer}");
        Console.WriteLine($"Path: {obj.GetReferencePath()}");
    }

If you're looking to modify the library for the sole purpose of modding UE Explorer, I recommend you to clone or fork this repository and install UE Explorer within your UELib/src/bin/Debug/ folder, or change the project's configuration to build inside of the UE Explorer's folder.

Compatible Games

This is a table of games that are confirmed to be compatible with the current state of UELib, the table is sorted by Package-Version.

Beware, opening an unsupported package could crash your system! Make sure you have saved everything before opening any file!

Note UE3 production-ready packages are often compressed and must first be decompressed, Unreal Package Decompressor by Gildor is a tool that can decompress most packages for you; for some games you need a specialized decompressor, see for example RLUPKTool.

Want to add support for a game? See adding support for new Unreal classes

Do you know a game that is compatible but is not listed here? Click on the top right to edit this file!

How to contribute

• Open an issue
• Or make a pull-request by creating a fork of this repository, create a new branch and commit your changes to that particular branch, so that I can easily merge your changes.

Special thanks to

• Epic Games for UDN: Packages (general package format)
• Antonio Cordero Balcazar for UTPT (game support) and documentation (format)
• Dmitry Jemerov for unhood (early UE3 format)
• Konstantin Nosov for providing help and UE Viewer (game support)
• Contributors