Table of Contents

Your First Mod

This guide builds a small mod that shows a message at the start of every day, with a setting to turn it off. It uses a mod class, a setting, an event, and some text—representing the core components of most Timbn mods. It takes about ten minutes.

You need the .NET SDK, Graveyard Keeper 2 with BepInEx for Graveyard Keeper 2 installed, and Timbn Core in the game's BepInEx/plugins folder.

The project below is written out by hand so you can see every part. To skip it, run dotnet new gk2mod -n MyFirstMod (see Getting Started) and carry on from The Mod Class.

The Project

Make a folder and add a MyFirstMod.csproj. Change GameDir if the game is installed somewhere else.

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.1</TargetFramework>
    <AssemblyName>MyFirstMod</AssemblyName>
    <Version>1.0.0</Version>
    <LangVersion>latest</LangVersion>
    <Nullable>enable</Nullable>
    <DebugType>embedded</DebugType>
    <ImplicitUsings>enable</ImplicitUsings>
    <GameDir>C:\Program Files (x86)\Steam\steamapps\common\Graveyard Keeper 2</GameDir>
    <RestoreAdditionalProjectSources>https://nuget.bepinex.dev/v3/index.json</RestoreAdditionalProjectSources>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="BepInEx.Core" Version="5.*" />
    <PackageReference Include="BepInEx.PluginInfoProps" Version="2.*" PrivateAssets="all" />
    <PackageReference Include="UnityEngine.Modules" Version="6000.3.9" IncludeAssets="compile" />
  </ItemGroup>

  <ItemGroup>
    <GameAssembly Include="Assembly-CSharp;Assembly-CSharp-firstpass;LazyBearTechnology;Sirenix.Serialization;Unity.Addressables;Unity.ResourceManager;Unity.TextMeshPro;UnityEngine.UI" />
    <Reference Include="@(GameAssembly)">
      <HintPath>$(GameDir)\GraveyardKeeper2_Data\Managed\%(Identity).dll</HintPath>
      <Private>false</Private>
    </Reference>
    <Reference Include="Timbn.GraveyardKeeperTwo.Core">
      <HintPath>$(GameDir)\BepInEx\plugins\Timbn.GraveyardKeeperTwo.Core\Timbn.GraveyardKeeperTwo.Core.dll</HintPath>
      <Private>false</Private>
    </Reference>
  </ItemGroup>

</Project>

DebugType embeds the debug symbols in the DLL, which a mod loaded from BepInEx/scripts needs. The game assemblies are listed because Core's calls use types from them, and the compiler asks for them as soon as your code touches one. Private is false so the game's and Core's DLLs are not copied into your output. BepInEx.PluginInfoProps writes a MyPluginInfo class from your project's name and version, which the mod class below reads.

The Mod Class

Add a Plugin.cs.

using BepInEx;
using BepInEx.Configuration;
using Timbn.GraveyardKeeperTwo.Core;
using Timbn.GraveyardKeeperTwo.Core.Framework;

namespace MyFirstMod;

[BepInPlugin(MyPluginInfo.PLUGIN_GUID, MyPluginInfo.PLUGIN_NAME, MyPluginInfo.PLUGIN_VERSION)]
[BepInDependency(TimbnCorePlugin.Guid, "2.0.0")]
public class Plugin : TimbnFrameworkPlugin<Plugin>
{
    internal static ConfigEntry<bool> Greet { get; private set; } = null!;

    protected override void BindConfig(ConfigFile config) =>
        Greet = config.Bind("General", "Greet", true, "Show a message at the start of every day.");

    protected override void OnAwake()
    {
        Text.Add("my_first_mod_hello", "Good morning, keeper!");

        Settings.While(Greet, () => Events.NewDayStarted(_ => TimbnUI.Notify("my_first_mod_hello")));
    }
}

Here is what each part does.

  • TimbnFrameworkPlugin<Plugin> is the base class every Timbn mod uses. It gives you Events, Settings, Text and the other properties used below. See Getting Started.
  • BindConfig runs before OnAwake and makes the setting players see in their config file or a config manager.
  • Text.Add registers the message under a key. The game shows text by key, so a notification takes the key, not the words.
  • Events.NewDayStarted runs your code at the start of every day. See Game Events.
  • Settings.While keeps the event hooked only while the setting is on, so switching it off in a config manager stops the message right away. See Settings.

You never undo any of this. Everything registered through those properties is owned by your mod and removed when it unloads.

Build and Run

dotnet build -c Release

Copy MyFirstMod.dll from the output folder into BepInEx/plugins/MyFirstMod/ in the game folder, then start the game and load a save. Sleep through a night and the message shows when the new day starts.

If you use BepInEx's ScriptEngine, put the DLL in BepInEx/scripts instead. Then you can rebuild and press F6 in-game to reload it without restarting the game.

Where Next

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