MonoMod

General purpose .NET assembly modding "basework", powered by cecil.
^{MIT-licensed.}

GitHub: All	NuGet: Patcher	NuGet: Utils	NuGet: RuntimeDetour	NuGet: HookGen

^{... or download fresh build artifacts for the last commit.}

Sections

• Introduction
• Using MonoMod
• Using ModInterop (ext)
• Using RuntimeDetour & HookGen (ext)
• FAQ

Special thanks to my patrons on Patreon:

• Chad Yates
• Sc2ad
• Raegous
• Chaser6
• Harrison Clarke
• KyleTheScientist
• Renaud Bédard
• leo60228
• Rubydragon
• Holly Magala
• Jimmy Londo (iamdadbod)
• Artus Elias Meyer-Toms

---

Introduction

MonoMod is a modding "basework" (base tools + framework).
Mods / mod loaders for the following games are already using it in one way or another:

• Terraria: tModLoader, TerrariaHooks
• Hollow Knight: HollowKnight.Modding
• Celeste: Everest
• Risk of Rain 2: BepInExPack (BepInEx + MonoMod + R2API)
• Enter the Gungeon: Mod the Gungeon
• Rain World: RainDB via Partiality
• Totally Accurate Battle Simulator: TABS-Multiplayer
• Salt and Sanctuary: Salt.Modding
• Nimbatus: Nimbatus-Mods via Partiality
• Dungeon of the Endless: DungeonOfTheEndless-Mod via Partiality
• FEZ: FEZMod (defunct)
• And many more! Ping me on Discord if your mod uses MonoMod!

It consists of the following modular components:

• MonoMod.Patcher: The ahead-of-time MonoMod patcher and relinker.
• MonoMod.Utils: Utilities and helpers that not only benefit MonoMod, but also mods in general. It contains classes such as PlatformDetection, FastReflectionHelper, DynamicMethodHelper, DynamicMethodDefinition, DynDll and the ModInterop namespace.
• MonoMod.DebugIL: Enable IL-level debugging of third-party assemblies in Visual Studio / MonoDevelop.
• MonoMod.Core: The core upon which runtime method detouring is built.
• MonoMod.RuntimeDetour: A flexible and easily extensible runtime detouring library, supporting x86/x86_64 on .NET Framework, .NET Core, and Mono.
• MonoMod.RuntimeDetour.HookGen: A utility to generate a "hook helper .dll" for any IL assembly. This allows you to hook methods in runtime mods as if they were events. Built with MonoMod and RuntimeDetour.
• MonoMod.Backports: A collection of BCL backports, enabling the use of many new language and library features, as far back as .NET Framework 3.5.

Why?

• Cross-version compatibility, even with obfuscated assemblies.
• Cross-platform compatibility, even if the game uses another engine (f.e. Celeste uses XNA on Windows, FNA on macOS and Linux).
• Use language features which otherwise wouldn't be supported (f.e. C# 7 in Unity 4.3).
• Patch on the player's machine with a basic mod installer. No need to pre-patch, no redistribution of game data, no copyright violations.
• With HookGen, runtime hooks are as simple as On.Namespace.Type.Method += (orig, a, b, c) => { /* ... */ }
• With HookGen IL, you can manipulate IL at runtime and even inline C# delegate calls between instructions.
• Modularity allows you to mix and match. Use only what you need!

---

Debugging mods that use MonoMod

See Debugging.