automod docs

Creating Unreal Engine game mods is tedious, error-prone, and time-consuming. To help with the process, automod can automatically generate a mod with patched .uasset properties from succinct TOML patch files, which may include embedded regular expressions and Scala, TypeScript, JavaScript, Kotlin, and/or Python patchlets.

Unity games are supported the same way: automod patches asset bundles and raw files using class-scoped TOML or script patch files, and packages the result with an embedded installer. This enables complex patching tasks with significantly lower manual effort, all with patch auto-merging support.

How automod works

Unreal Engine mods

For each mod you define, automod produces a <mod-name>.zip (or .7z) archive containing the patched .utoc/.ucas/.pak files, ready to be uncompressed into the game’s Content\Paks\~mods folder. Under the hood it runs a fixed pipeline:

1. Extract the target .uasset/.uexp files from the game’s Paks directory using retoc/repak.
2. Convert them to UAssetAPI’s .json format in-process using uasset4j (the JVM port of UAssetAPI).
3. Patch the JSON: automod loads all TOML patch files from the patches directory in order (see the TOML Patch File Schema and Patch Auto-Merging), optionally followed by your custom code patches.
4. Regenerate the patched .uasset/.uexp files in-process using uasset4j.
5. Repack them into .utoc/.ucas/.pak using retoc/repak, and package everything into a <mod-name>.zip (or .7z) archive.

Unity mods

Unity mods patch the game’s serialized asset files (*.assets) and raw files (e.g. Assembly-CSharp.dll) in place, packaged with an embedded installer:

1. Decode the target bundles with asset4j (the JVM port of AssetsTools.NET) using the game’s ttmap schema (see the Unity Modding guide).
2. Patch the decoded objects via class-scoped TOML (ClassName@bundle.toml, .@ JSONPath) or script patches (.kt, .js, .py, etc.), and raw files via whole-file script patches (v.orig/v.current).
3. Re-encode the bundles in-process with asset4j.
4. Package everything into a <mod-name>.zip (or .7z) archive that embeds the install.py installer, which copies the files into the game’s data directory, backing up the originals for --restore/-r.

You only write the patch files; everything else is automated. The Getting Started section walks through the setup, while the Guide explains the patching concepts in detail.