Become a LoL Dev/Modder - Step by Step Guide on How to modify the LoL Client Code

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Welcome to this updated tutorial on how to modify the LoL Client.
You will be able to create your own modifications (mods) and share them with lots of people.

Introduction:

My english might not be the best as I'm still learning it.
The Client is coded in as3 ( Action Script 3 bytecode ) and if you start from 0 knowledge, it's intuitive.
I had to start form 0 too and with almost no guide on the internet. But don't be sad, I'm here to help you as much as I can!


Warnings:

Riot does not like people who modify the client and some users had particular warnings about what they have created, so pay attention at what you create.
I don't take any responsabilities if Riot contact you and warns you.


To get started:

Enought warning, let's get started!
You will need RABCDAsm (see the full docs. here Readme.md )
Any text editor, I suggest Notepad++

The RABCDAsm link I gave you is not compiled yet, that's why I'v included everything you need (and already compiled) on the mod pack down below
I'm not forcing you to download the .zip below (that's why you have full access at the uncompiled version)

The .zip doesn't contains 2 extra .bat files that I wanted to include, it's because some of you might be scared (I will talk about the .bat files down below)

You have to know what you are going to modify and where are the files.
You can find the files right here:

\RADS\projects\lol_air_client\releases\0.0.X.XX\de ploy\lib
\RADS\projects\lol_air_client\releases\0.0.X.XX\de ploy\mod

The lib folder and what is inside is pretty intuitive to know whta there is inside ex: ClientLibGame.dat
But the man folder is a little bit "hard" to understand, so here is a list of what they include:
I'm not able to create spoilers tabs, so I'll put the list here


Decompiling:

We are going to use mod_man.dat as example
Be sure to do a backup so you can revert and remove your unworking/glitchy mods
Now that you know what you whant to modify, go to your RABCDAsm folder, hold shift and press Right-click, now click "Open command window here"
In the console type:

abcexport mod_man.dat

In that case you will obtain 2 new files .abc named mod_man-0.abc and mod_man-1.abc
We are looking for the biggest one (in Kb/Mb) so we will pick mod_man-1.abc and type into the console (or simply drag the file):

rabcdasm mod_man-1.abc

Wait for the decompression and when it's done, you can now start by going into the exported folder and directly go into the com folder (where magics comes from OuO)
You have to edit files named .class.asasm and NOT .script.asasm
I suggest by typing into the search bar .class.asasm and order the items by size (the big sizes on top) so you can edit the best files

Recompiling:

When you finished ruining the code of the client ( ) you can now repompress it and test it.
In the console just type:

rabcasm

then go to your main folder (mod_man-1) and find the file .main.asasm (usually you can find it by size) AND drag it into the console, then press enter.
Now pay attention !
Type abcreplace then drag your .dat file, then the number of the folder in that case we have mod_man-1 so the number will be 1 (I know you mind is already blowup but trust me, I'll teach you how to make it automatically ) and finally drag the new file generated into your main folder mod_man-1.main.abc
Your final code should look something like this:

abcreplace "C:\Users\HP\Desktop\moLoL\mod_man.dat" 1 "C:\Users\HP\Desktop\moLoL\mod_man-1\mod_man-1.main.abc"

Congratulations! You compiled your first mod!


About the .bat files:

This process that I showed you takes too much time, so I made myself a simple .bat script to auto decompile/compile my mods way faster!
anyDatDecompiler.bat --> You can decompile all .dat files on the same folder (useful for the files into the lib folder) also makes a file named tree.txt appears, so you can search a bit faster if you have lots of files.
Auto Decompress/Recompress --> I always use this to decompile and recompile automatically !


Useful links:

I told you that I was going to help you!
If you have any questions about the code fell free to ask me with no problem (take a look at this document first so I don't get spammed )
avm2overview.pdf
LoL Devs
(I'll add more if I find something)


Video
When I have some free time I'll make a short video, so you can see how I work! (And hear my Swiss voice )


Virus scans:

Jotti's Scan 0/22
Virus Total 0/55

I'v made this guide personally and it took me 40mins, so a thanks vould be appreciated! (feeling famous online)

Thanks for reading folks and happy modding