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Creating mods with sideloader

IMPORTANT: This guide is technical and is aimed at people who work on UI tools for sideloader and those who want to make mesh/prefab/material replacements.
If you want to make skin mods, use SkinPacker for now.

Sideloader mod format

A sideloader mod is a ZIP archive renamed to .h3mod that contains the following files:

• PNG files (optional, used for textures)
• Unity asset bundles (for meshes, prefabs and materials)
• manifest.json (required)

For now, to create mesh/prefab/material replacements, you have to manually create asset bundles via Unity. A preferred way for now is to use AssetBundle Browser tool for Unity which allows you to easily compose and build asset bundles.

manifest.json

Manifest file contains metadata about the mod as well as information for sideloader about how to map the assets in the zip archive to in-game assets.

For more technically inclined, check out manifest's schema file and schema docs that contain technical info about the schema file.

Example manifest file:

{
  "manifestRevision": "1",
  "guid": "horse.coder.carrot_gun",
  "name": "Carrot Thompson M1A1",
  "version": "1.0.0",
  "description": "This is an example gun",
  "assetMappings": [
    {
      "type": "Texture",
      "target": "::m1a1_BaseColor:",
      "path": "thompson.png"
    }
  ]
}