Plugin Manager

Unity Plugin Manager


Unity Plugin Manager (herein, UPM) is a tool for creating plugins and mods for games developed with the Unity engine.

How it works

UPM injects a static constructor into the GameObject class found within the UnityEngine namespace. This way, it is able to execute code before anything else in the game. Using this, it loads plugins from a folder named “Plugins” in the game’s folder, and instantiates any MonoBehaviour derivatives with the [OnGameInit] attribute.


In order to build UPM or create plugins, you will need the .NET Core SDK and at least one of the following:

  • An installation of Unity 5.x or 2017.x
  • A game developed in Unity 5.x or 2017.x

Within the UPM repository is a directory named Managed.UnityEngine. This directory needs to contain specific files from one of the aforementioned prerequisites.

Option A: Unity Installation

  1. Browse to your Unity installation directory (usually C:\Program Files\Unity [version]\Editor)
  2. Browse to Data\Managed and copy UnityEngine.dll to the Managed.UnityEngine\Managed directory in the UPM repository
  3. If it exists, browse to Data\Managed\UnityEngine and copy everything except UnityEngine.dll to the Managed.UnityEngine\Managed directory in the UPM repository
  4. Browse to Data\UnityExtensions\Unity\GUISystem\Standalone and copy UnityEngine.UI.dll to the Managed.UnityEngine\Managed directory in the UPM repository

Option B: Game

  1. Browse to the game’s Managed directory (usually inside the game’s Data folder)
  2. Copy every file with UnityEngine in its name to the Managed.UnityEngine\Managed directory in the UPM repository

You should now be able to compile UPM by either using Build.All.bat, PluginManager.sln or manually calling dotnet build in the appropriate directories.


After building UPM, you should have at least the following files:

  • PluginManager.Setup.exe (PluginManager.Setup/bin/...)
  • PluginManager.Core.dll (PluginManager.Core/bin/...)
  • Mono.Cecil.dll (PluginManager.Setup/bin/...)

Any other files are not necessary for usage of UPM.

Place the aforementioned files into the directory where your target game is located, and run PluginManager.Setup.exe (using Mono to do so, if not on Windows)

If UPM installed successfully, you should see a message stating UPM installed.

You are now free to create a Plugins directory and place your plugins in there.

Creating plugins

The creation of plugins is a relatively simple process.

  1. Make a new folder for your target game in the Managed.Games folder, if one does not exist
  2. Put the Assembly-CSharp.dll, Assembly-UnityScript.dll and/or Assembly-Boo.dll files from your target game in that folder, if they are present in its Managed folder
  3. Make a new folder for your plugin in the Plugin.Projects folder
  4. Copy one of the templates into that folder (NET46 is only for Unity 2017 projects using the new Mono runtime!)
  5. Edit Config.props to point to your target game

You can compile your plugin by opening a command prompt in its folder and entering dotnet build.

Refer to the sample plugin as an example of how to get started.