Create your first mod

This walkthrough builds a small mod that logs a message before KSA starts. It uses a lifecycle callback and does not require constructor injection.

Create a project

Install the .NET 10 SDK, then create a class library and add the StarMap API package:

dotnet new classlib --framework net10.0 --name HelloStarMap
cd HelloStarMap
dotnet add package StarMap.API

Use the StarMap.API package version compatible with the loader you are targeting. It may have a different version number from the StarMap application. Add <PlatformTarget>x64</PlatformTarget> to the project's main <PropertyGroup>:

<PropertyGroup>
  <TargetFramework>net10.0</TargetFramework>
  <PlatformTarget>x64</PlatformTarget>
  <ImplicitUsings>enable</ImplicitUsings>
  <Nullable>enable</Nullable>
</PropertyGroup>

The project name produces HelloStarMap.dll by default, which will match the entry assembly name below.

Add the entry class

Replace the generated class with:

using StarMap.API;

[StarMapMod]
public sealed class HelloStarMap
{
    [StarMapBeforeMain]
    public void Initialize()
    {
        Console.WriteLine("Hello from my mod.");
    }
}

This entry class uses a parameterless constructor. For constructor injection and the services registered by StarMap, see the constructor-injection guide.

Add mod.toml

Create mod.toml in the project root:

name = "HelloStarMap"

[StarMap]
EntryAssembly = "HelloStarMap"

name is the KSA mod ID. Keep it the same as the mod folder and KSA manifest ID. EntryAssembly is the assembly name without .dll.

Build and install

Build the project:

dotnet build -c Release

Copy mod.toml, the built HelloStarMap.dll, its .deps.json, and any private dependencies from bin\Release\net10.0\ into a folder named HelloStarMap in either supported mod location. Keep mod.toml beside the DLL. Enable the matching mod ID in KSA's manifest, then start the game with StarMap.exe.

When loaded, the mod writes its message to the StarMap console before KSA starts.