Getting Started

This guide walks you through setting up SteamNetworkLib in a Unity game mod using MelonLoader and implementing the minimal loop.

Installation

Prerequisites

MelonLoader installed on the target Unity game
Steam client running
Unity game with Steam integration
Basic C# and MelonLoader modding knowledge
Visual Studio or VS Code

Add SteamNetworkLib to Your Mod Project

Target .NET Standard 2.1 (works for Mono and Il2Cpp) and reference SteamNetworkLib:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netstandard2.1</TargetFramework>
    <AssemblyTitle>YourAwesomeMod</AssemblyTitle>
    <AssemblyVersion>1.0.0</AssemblyVersion>
  </PropertyGroup>
</Project>

Add references to:

MelonLoader.dll
UnityEngine.dll
Assembly-CSharp.dll
SteamNetworkLib.dll

Download the matching SteamNetworkLib DLL from the GitHub releases page, keep that DLL in your mod project or local dependency folder, and reference the runtime-specific binary:

Mono mods/configurations must reference the Mono release DLL
Il2Cpp mods/configurations must reference the Il2Cpp release DLL

Do not mix these references across build targets, and do not point your mod project at a sibling ..\SteamNetworkLib\bin\... source checkout.

If your mod has separate Mono and Il2Cpp configurations, reference the downloaded DLLs conditionally in your .csproj:

<ItemGroup Condition="'$(Configuration)'=='Mono' or '$(Configuration)'=='MonoDebug'">
  <Reference Include="SteamNetworkLib">
    <HintPath>libs\SteamNetworkLib\Mono\SteamNetworkLib.dll</HintPath>
  </Reference>
</ItemGroup>

<ItemGroup Condition="'$(Configuration)'=='Il2cpp' or '$(Configuration)'=='Il2cppDebug'">
  <Reference Include="SteamNetworkLib">
    <HintPath>libs\SteamNetworkLib\Il2cpp\SteamNetworkLib.dll</HintPath>
  </Reference>
</ItemGroup>

Minimal mod setup

using MelonLoader;
using SteamNetworkLib;

public class YourAwesomeModMain : MelonMod
{
    private SteamNetworkClient client;

    public override void OnInitializeMelon()
    {
        // Optional: configure network rules (relay, session policy, channels)
        var rules = new SteamNetworkLib.Core.NetworkRules
        {
            EnableRelay = true,
            AcceptOnlyFriends = false
        };

        client = new SteamNetworkClient(rules);
        if (client.Initialize())
        {
            // Optional: subscribe to events
            client.OnLobbyCreated += (s, e) => MelonLogger.Msg($"Lobby: {e.Lobby.LobbyId}");
        }
    }

    public override void OnUpdate()
    {
        client?.ProcessIncomingMessages();
    }

    public override void OnDeinitializeMelon()
    {
        client?.Dispose();
    }
}

Best Practices

Use unique prefixes for your mod's data keys to avoid collisions with other mods. See Data Synchronization for details.

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