Transport Fever 3 Modding Guide: Files, First Mod, and Publishing

This Transport Fever 3 modding guide starts with the game's own documentation. A mod is a separate folder containing resources and metadata. Urban Games advises creators to leave the installation files alone and put changes in a mod instead. The official examples include a small configuration change and a placeable 3D asset, so you can choose a starting point that matches your skills.

The official modding introduction lists vehicle repaints, new vehicles and assets, configurable constructions, configuration changes, and model rebalancing as common projects. A configuration change requires much less 3D work than a new train. Start with the narrowest example that demonstrates your idea.

Create the mod folder

The Mod Definition page shows this general layout:

mods/
  author_example_mod/
    _metadata/
      modinfo.json
      description.html       # optional
      0.png                  # optional preview
    content/
      mod.script.tl          # optional script
    mod.json
    strings.json             # optional translations

The folder name is not the game's technical identifier. The wiki recommends an <author>_<modname> style name and keeping it aligned with the ID in mod.json. Game resources such as models, textures, and scripts belong in content/; _metadata/ holds the information displayed in the Mod Browser.

Not every mod needs every optional file. For instance, a placeable asset needs its model and construction resources, whereas the official configuration-change example uses the basic definition and metadata files plus mod.script.tl. Copy the matching official demo when beginning rather than adding empty files for features you do not use.

Define the mod in mod.json

mod.json is the technical definition. Its modId identifies the mod independently of where it is installed; revision tracks updates. The wiki also documents severityAdd, severityRemove, visible, cosmetic, dependencies, and incompatibilities. A minimal starting shape is:

{
  "modId": "author_example_mod",
  "revision": 1,
  "severityAdd": "None",
  "severityRemove": "Warning",
  "visible": true,
  "cosmetic": false
}

Choose severity values according to the effect of the mod. The documented choices are None, Warning, and Critical. Removing a mod that supplies a cargo type or another save-dependent resource can have more serious consequences than removing a purely visual change. The wiki says cosmetic: true is for genuinely cosmetic mods; gameplay changes such as altered vehicle capacities or production output should not be marked cosmetic. See the field definitions and examples before publishing.

Add browser metadata and text

_metadata/modinfo.json provides the display name, short summary, and description. The official guide says the name should be at most 32 characters and the summary at most 100; neither should contain line breaks. It also documents localized names and descriptions, author information, supported tags, and an optional URL.

strings.json is available for text used inside the mod. The wiki shows language-keyed strings with an English fallback. Use it when your asset labels or parameter names need localization. Keep technical IDs stable across languages and translate the visible strings.

For a visual preview, the Mod Definition page documents numbered PNG files in _metadata/; 0.png is used in the browser grid. The page recommends 1920 × 1080 images. This is optional for a local prototype but useful when other players need to recognize the mod.

Choose a first project

Configuration change: The official demo config mod changes a train braking setting. It demonstrates a small script-based override using mod.json, _metadata/modinfo.json, and mod.script.tl. Work from the downloadable demo and change one value at a time. Test the result in a separate game before adding more changes.

Placeable asset: The official demo asset uses a model, mesh, textures, and construction/script files in addition to the mod definition. This route is suitable if you want to learn the 3D pipeline. Copying only the metadata will not create a working asset; the model resources must also be present and correctly referenced.

Vehicle repaint: The introduction describes repaints as a possible entry point for creators who already have image-editing skills. Use the linked vehicle repaint documentation for the correct resource setup rather than assuming a texture alone is sufficient.

For each project, verify that the game recognizes the mod, load it in a test game, check the intended change, and inspect errors before sharing. Keep a backup of any save used for testing a gameplay-changing mod.

Share and update your mod

Transport Fever 3 has an integrated Mod Browser powered by mod.io. Urban Games says mods are supported across PC and consoles through this browser. The official support page also says Steam Workshop is not included and manual sharing outside the browser remains possible.

The wiki's publishing guide describes the game's Mod Hub and its My Mods area for uploads. That page is marked as an old revision, so check the current in-game flow before following its exact buttons or folder locations. When updating a published mod, increase revision in mod.json and check the current publishing instructions so the update reaches the intended mod entry.

Before uploading, confirm that you have permission to distribute every model, texture, sound, and script in the package. The official publishing guide requires mods to be free and to comply with the platform's terms.

Common questions

Where should I edit the base game's files?

Create a separate mod folder. The official introduction specifically advises against changing the installation directory.

Are mod.json and modinfo.json interchangeable?

No. mod.json supplies the technical ID and behavior, while _metadata/modinfo.json supplies information shown in the Mod Browser.

Does Transport Fever 3 use Steam Workshop?

The official support FAQ says it uses an integrated mod.io browser instead. Manual sharing is still possible.

Sources: Official modding introduction, Mod Definition, publishing guide, and support FAQ.