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Your first mod in CSharp

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Bartholomew Ho edited this page Nov 9, 2026 · 1 revision

This walks you through a mod that adds Repair to FH2 ANNA's menu and warns you when you go over 300 km/h. It takes about ten minutes. Prefer VB.NET? See Your first mod in VB.

1. What you need

  • The .NET 10 SDK, plus Visual Studio 2026 or VS Code if you like an editor.
  • The game with FH2 Mod Platform for .NET installed: see Installing.
  • For the ANNA entry: the FH2 ANNA mod. Without it, the entry is just left out.

2. Get the SDK package

The release zip has the SDK as a NuGet package in sdk\FH2ModPlatform.<version>.nupkg.

  1. Copy it into a folder of its own, for example C:\FH2Sdk\.

  2. Tell NuGet about that folder, once:

    dotnet nuget add source C:\FH2Sdk --name FH2

The package is also on GitHub Packages. GitHub asks for a personal access token with read:packages even for public packages, so the folder is simpler.

3. Make the project

dotnet new classlib -n MyFirstMod -f net10.0
cd MyFirstMod
del Class1.cs

Replace MyFirstMod.csproj with:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <!-- Your Mod class: namespace.ClassName -->
    <FH2ModType>MyFirstMod.MyFirstMod</FH2ModType>
    <!-- Your game's fh2-mods folder: builds are copied there for you. -->
    <FH2ModsDir>D:\Games\Azimuth\fh2-mods</FH2ModsDir>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="FH2ModPlatform" Version="0.9.0" />
  </ItemGroup>
</Project>

4. Write the mod

MyFirstMod.cs:

using FH2;
using FH2ModPlatform;

namespace MyFirstMod;

public sealed class MyFirstMod : Mod
{
    public override ModInfo Info => new("MyFirstMod", "1.0.0")
    {
        Description = "Repair from ANNA, and a speed warning.",
    };

    private bool _warned;

    protected override void OnInit()
    {
        Log("hello!");

        // FH2 ANNA's menu (D-pad down while driving).
        ANNA.Items("Car").Add("Repair", () => Player.Car?.Repair());

        // Once a frame while you drive, on the game's thread.
        Game.Tick += () =>
        {
            var car = Player.Car;
            if (car is null) return;

            if (car.SpeedKmh > 300 && !_warned) UI.Notify("Slow down", $"{car.SpeedKmh:F0} km/h");
            _warned = car.SpeedKmh > 300;
        };
    }
}

What's going on:

  • Info is your mod's name and version. They show in the game and in the log.
  • OnInit runs once, when the game starts. Set things up there and return quickly.
  • Player.Car is your car, or null when you're not driving. That's why there's a ?. and an is null check.
  • Game.Tick runs on the game's thread, so the FH2 classes can be used straight away. See Threads.

5. Build and run

dotnet build

The build copies the mod to fh2-mods-dotnet\MyFirstMod\. Start the game, drive, press D-pad down and pick Car > Repair.

To see your Log lines, press ~ in the game or open fh2-mods\platform.log.

6. Change it without restarting

Turn on MODS > Installed mods > Platform.NET > Reload .NET mods when rebuilt. Now every dotnet build swaps the new code into the running game. See Reloading and debugging.

7. Ship it

For players, publish it as one DLL:

dotnet publish -c Release -p:FH2ModHosting=Aot

Give players bin\Release\net10.0\win-x64\publish\MyFirstMod.dll. It goes in fh2-mods\ and needs no .NET runtime. See Hosted or NativeAOT?.

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