Before you start disassembling Conquer, it's important that you understand the basics of assembly. For a tutorial on Assembly Languages, check out Tutorials Point. They cover the basics pretty well. This guide will help you disassemble Conquer for the first time using Hopper Disassembler, which is a reverse engineering tool I use to translate compiler machine languages into higher-level assembly language. Hopper is a paid program; therefore, I will not be providing a copy through this thread. I recommend purchasing a license and would definitely never suggest searching for one of the many, easy-to-find, pirated copies out there.
Hopper can only be installed on Linux and Mac OS. Therefore, if you're using Windows, you'll need to create a virtual machine. For simplicity, I recommend using either Oracle VirtualBox or VMWare Workstation Player; both have tutorials for running either Linux or Mac OS in a VM. I use Ubuntu 18.04 with VMWare Player. If you need a tutorial, check out this video. Once your virtual machine is set up, install Hopper Disassembler and you're ready to go.
Now that Hopper is set up, download a Mac client for Conquer. All you need is the dmg file (you don't need to install it). After downloading the file, open it in 7-Zip. Navigate to "Conquer\Conquer.app\Contents\ConquerGameExe.app\Contents\MacOS". This path might be different depending on the client version you downloaded. Extract the ConquerGameExe file and open it in Hopper. Hopper will automatically detect the compiler, so don't change any of its analysis settings. After a few minutes, you should have analyzed assembly. See the picture below.
You can search for classes and methods using the Procs tab. Give it a try with a packet name from the wiki. After finding a method, switch between views along the top bar. One particularly helpful view is the "Show Pseudo Code of Procedure" view. This shows the assembly in a C-like assembly syntax. It's not perfect, but it does help show the flow of logic.
You can also search for text using the Strs tab. Once you find a string you're looking for (ex. Monster.dat), you can see all references to the string in the right panel. This can help a lot when trying to understand how files are read by the client.
That's really it. I'm definitely not as experienced as others when it comes to reverse engineering, but Hopper does make it easier for those who have assembly knowledge but no knowledge on the structure of the game client's assembly. This won't help you develop bots or hacks on Windows, but it is helpful when writing a private server. Happy disassembling!