I'm no longer maintaining this tool.

IL2CPP Patcher

A tool for Android modders who are too lazy to mod multiple versions of an app over and over again. For libil2cpp.so modding only. If you're modding a different file, such as Assembly-CSharp.dll, please look for other tools.

Getting Started

1. For developers
2. For users
3. What is the mod file?

Prerequisites

• A computer
• Il2CppDumper: please Google how to use. You will need this to get a dump.cs file
• JDK 8 for developers, JRE / JDK 8 for users (both are ok)
  • JDK 9 should work but I had a lot of troubles with JDK 9 during development so it's better to use 8

For developers

Click here

For users

1. Download the latest release

2. Open a terminal, cd to the directory where you put the .JAR file

   • For example, if the .JAR file is in E:/Download/JAR/Ill2cppPatcher.jar, you type this into the terminal

   E:
   cd E:/Download/JAR

3. Type this in

   java -jar Il2cppPatcher.jar <FULL_PATH_TO_IL2CPP.SO_FILE> <FULL_PATH_TO_DUMP.CS_FILE> <FULL_PATH_TO_MOD_FILE>

   So if your files are E:/Folder1/libil2cpp.so, D:/Folder2/dump.cs, C:/Folder3/mod.txt, you type in

   java -jar Il2cppPatcher.jar "E:/Folder1/libil2cpp.so" "D:/Folder2/dump.cs" "C:/Folder3/mod.txt"

4. Do make a backup of the libil2cpp.so file beforehand. The application will not create a backup for you

5. If you still don't understand, refer here for a guide with screenshots.

Mod file

So what exactly is the mod file that is the 3rd argument you need to provide to the app? A mod file contains all the changes needed to create a mod. I will assume that you know how to do mods using IDA. A mod file contains the method names and the hex changes that will be applied to the libil2cpp.so file.

For example, you need to mod a method called public int get_HP(); // 0x123456, and in that method, the modification you do is to change the bytes values starting at address 0x123460 from 0x0011 to 0xAABB. So the mod file will be something like this

#
Get HP
public int get_HP(); // 0x123456
0x123460 0x2 00 11 AA BB

Let's see what each line does:

#

This is the delimiter. Every mod option needs a # character at the start. So if you have two options in your mod, let's say, Godmode and High damage, then you need two # at the start of each.

Get HP

This is the name of the mod. It has absolutely no meaning to the application, it's just there so that you know which option is which.

public int get_HP(); // 0x123456

This is the method. You need to copy this fully from dump.cs and every method must be in this format: something functionName(); // 0xsomeNumber

0x123460 0x2 00 11 AA BB

This means the modification starts at address 0x123460 and has length of 0x2 (it's 2), and changes the bytes 0x0011 to 0xAABB. You can get this format very quickly by pressing CTRL+ALT+P in IDA and copy paste from there.

You can see a more in-depth example here. It's a mod for the game アリス・ギア・アイギス.

What to do when the Android app has an update?

This application works on an assumption that the more core methods will not change between small updates. And that is the fact with many Android app. So you only need to mod the first time and note your modifications down. For all future updates, you only need to extract the libil2cpp.so file and generate dump.cs. Then pass these two files, together with the mod file to the application, and you have a newly-modded libil2cpp.so file! In case there are changes between updates, the application will print out which mod options are not working correctly so that you can pinpoint on only the outdated options.