Creating an Addon Project

If you want to create a New Horizons project you have a few options, depending on your use case.

Using the New Horizons Template

Use this method if you are not planning to use any custom scripts in your mod. This is helpful if you’d prefer to avoid installing Visual Studio, but also limits what you can do in your mod. You will be limited to features of the base game like character dialogue, Nomai text, tornados, black holes, or whatever else you might find in the New Horizons Examples Mod.

Making a GitHub Repository

To get started, you’ll need to click the green “Use This Template” button on the New Horizons addon template GitHub repository.

Set the name to be something informative, likely the name of your mod. Once you submit your mod to the Outer Wilds Mod Database it is best to not change this name, so choose wisely. Note that this name will not appear in the mod manager or website, that comes later.
The description is what will appear in the mod manager under the mod’s name, you can always edit this later
You can set the visibility to what you want; But when you go to publish your mod, it will need to be public

Open The Project

Now clone the repository to your local computer and open it in your favorite editor (we recommend VSCode).

Project Layout

.github: This folder contains special files for use on GitHub, they aren’t useful right now but will be when we go to publish the mod
planets: This folder contains a single example config file that destroys the Quantum Moon, we’ll keep it for now so we can test our addon later.
.gitattributes: This is another file that will be useful when publishing
default-config.json: This file is used in C#-based mods to allow a custom options menu. New Horizons doesn’t support a custom options menu, but we still need the file here in order for the addon to work.
manifest.json: This is the first file we’re going to edit, we need to fill it out with information about our mod
- First you’re going to set author to your author name. This should be the same name that you used when creating the GitHub repo.
- Next, set name to the name you want to appear in the mod manager and website.
- Now set uniqueName to your username followed by a dot (.), followed by your mod’s name in PascalCase (no spaces and new words have capital letters). For example if my username was “Test” and my mod’s name was “Really Cool Addon”, I would make the unique name Test.ReallyCoolAddon. Once you have submitted your mod to the Outer Wilds Mods Database you should never change this unique name.
- You can leave version, owmlVersion, and dependencies alone.
NewHorizonsConfig.dll: This is the heart of your addon. Make sure to never move or rename it.

Testing The Addon

In order for the addon to show up in the manager and subsequently be loaded into the game you’ll need to ensure that it’s located in %APPDATA%\OuterWildsModManager\OWML\Mods (or ~/.local/share/OuterWildsModManager on Linux). How you choose to do this is up to you. You could manually copy the mod folder over every time, you could setup an automated VSCode Launch Configuration to do it every time you press F5, or you could simply keep your mod in that folder. The last option, while the easiest, is not recommended as downloading another version of your mod can overwrite your current working copy.

Once put in the Mods folder the manager will display your mod without a description or download count. You can then launch the game to see if your planets load in.

Checking In-Game

Now when you click “Start Game” and load into the solar system, you should be able to notice that the Quantum Moon is gone entirely. This means that your addon and its configs were successfully loaded. You may now delete the existing example config planet for the Quantum Moon if you’d like, assuming your goal wasn’t to delete it.

Adding support for custom scripts later

If you later decide you want to use custom scripts, follow the guide below for using the standard OWML template. Then, copy all your .json and .xml files into your new project. You may wish to move all your existing files in your GitHub repository into a new branch, then force push your existing project into your repository, or alternatively make a brand new repository.

Using the standard OWML Template

If you’d like the ability to use custom scripts, then you’ll want to make a typical Outer Wilds mod while making sure to include support for New Horizons. This will require Visual Studio and is a little more complicated, but will give you far more power over your mod.

Follow the OWML Getting Started Guide. However, when following the project creation wizard, make sure to tick the “Use New Horizons” checkbox when it shows up.

Adding New Horizons to an existing mod

If you have an existing mod that was made without New Horizons, adding New Horizons compatibility is very easy.

First, create a planets, systems, and translations folder inside your mod project, in the root folder of your mod. You’ll also want to make a few edits to your .csproj file in order to automatically copy those to your build. Open the .csproj file with a text editor or click the entry at the top of the Solution Explorer with the name of your mod. In the same <ItemGroup> that includes instructions to copy your manifest files, add these:

    <None Include="planets\**\*.*">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Include="systems\**\*.*">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
    <None Include="translations\**\*.*">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>

Then you’ll need to add some code for actually loading your planets and systems into your mod.

Download INewHorizons.cs and save it into your mod project somewhere.
Open your main mod file (ModName.cs) and add public INewHorizons NewHorizons; to your field definitions.
Add the following code to your Start() method:

// Get the New Horizons API and load configs
NewHorizons = ModHelper.Interaction.TryGetModApi<INewHorizons>("xen.NewHorizons");
NewHorizons.LoadConfigs(this);

This will make New Horizons automatically load any planets and systems you have set up, though if you’re making a more complicated mod you may prefer to load config files manually.