While BepInEx was originally designed for Unity games using the Mono backend, many modern Unity games now use IL2CPP, which converts managed code into native C++ for improved performance and security. Modding IL2CPP games is more complex, but BepInEx has evolved with tools and community support that make it possible to modify these games effectively with the correct setup and understanding.
Understanding IL2CPP Architecture
IL2CPP is a Unity scripting backend that converts C# code into C++ before compiling it into native binaries. This process removes easily accessible managed assemblies, which makes traditional modding methods more difficult compared to Mono-based games. As a result, developers cannot directly reference game DLL files in the same way they would with Mono.
Because IL2CPP games compile managed code into native code, runtime patching requires additional tools and generated assemblies. BepInEx addresses this limitation by using interop generation systems that recreate usable assemblies for developers. This allows modders to inspect and interact with the game’s structure even when original managed DLLs are not available.
Installing BepInEx for IL2CPP
Installing BepInEx for IL2CPP games requires downloading the specific IL2CPP build of the framework. Using the Mono version will not work for these games, so verifying the correct backend type is essential before installation. The IL2CPP package includes additional components necessary for generating proxy assemblies.
After extracting the files into the game’s root directory, the first launch may take longer than usual. During this initial run, BepInEx generates interop assemblies based on the game’s native binaries. Once this process is complete, the framework creates necessary folders and prepares the environment for plugin loading.
Developing Plugins for IL2CPP Games
Plugin development for IL2CPP games is slightly more advanced compared to Mono games. Developers must reference the generated interop assemblies instead of traditional managed DLLs. These assemblies act as bridges between the native game code and managed plugin code.
Harmony can still be used for patching methods, but identifying correct targets may require additional analysis tools. Developers often rely on advanced inspection utilities to explore method structures and class hierarchies. Although the process is more technical, it allows deep and powerful modifications once properly configured.
Common Challenges and Solutions
One of the most common challenges when modding IL2CPP games is handling frequent game updates. Since IL2CPP recompiles native code, even minor updates can change method addresses and break existing patches. Developers must regularly test and update their plugins to maintain compatibility.
Performance considerations are also important. Because IL2CPP games run natively, poorly optimized patches can affect performance if not implemented carefully. Efficient coding practices and selective patching help maintain smooth gameplay while still achieving desired modifications.
Future of IL2CPP Modding with BepInEx
As more Unity developers adopt IL2CPP, the demand for stable modding solutions continues to grow. BepInEx development has gradually improved IL2CPP support, making it more accessible for modders who want to work with modern game builds. Community contributions play a major role in expanding compatibility and documentation.
With ongoing improvements, IL2CPP modding is becoming more streamlined and reliable. Although it remains more complex than Mono-based modding, BepInEx provides one of the most structured and adaptable solutions available for handling IL2CPP environments.
FAQs
What is IL2CPP in Unity games?
IL2CPP is a Unity backend that converts managed C# code into native C++ binaries. This improves performance but makes modding more complex.
Can BepInEx fully support IL2CPP games?
BepInEx provides growing support for IL2CPP games. Compatibility depends on the game version and proper installation of the IL2CPP build.
Why does the first launch take longer after installation?
During the first launch, BepInEx generates interop assemblies from native binaries. This process can take several minutes depending on system performance.
Is plugin development harder for IL2CPP games?
Yes, it requires referencing generated interop assemblies and deeper technical understanding. However, it offers powerful customization once configured correctly.
Do IL2CPP game updates break mods?
They can, because updates may change method structures. Developers often need to update plugins after major game patches.
Conclusion
Modding IL2CPP Unity games presents unique technical challenges compared to traditional Mono-based environments. However, with the correct BepInEx IL2CPP build and proper setup, developers can still inject plugins, patch methods, and modify gameplay effectively. Understanding how interop generation works is essential for achieving stable results.
Although IL2CPP modding requires more advanced knowledge and frequent maintenance after updates, BepInEx continues to evolve as a reliable solution. Its expanding compatibility and strong community support ensure that even modern Unity games remain accessible to dedicated modders seeking deep customization.