MU Online Client Sources

This is my special fork of the Season 5.2 client sources uploaded by Luois.

The ultimate goal is to clean it up and make it compatible and feature complete to Season 6 Episode 3.

What I have done so far:

• 🔥 The framerate has been increased.
  • By default, it uses V-Sync without fps limit. If V-Sync is not available, it limits to 60 fps.
  • The options menu includes a checkbox to reduce effects to achieve higher frame rates.
  • Chat commands:
    • Change FPS-Limit: $fps <value>
    • Enable V-Sync: $vsync on
    • Disable V-Sync: $vsync off
• 🔥 Optimized some OpenGL calls by using vertex arrays. This should result in a better frame rate when many players and objects are visible.
• 🔥 Added inventory and vault extensions.
• 🔥 The master skill tree system was upgraded to Season 6
• 🔥 Unicode support: The client works with UTF-16LE instead of ANSI in memory. All strings and char arrays have been changed to use wide characters. Strings coming from files and the network are handled as UTF-8.
• 🔥 Replaced the network stack with MUnique.OpenMU.Network to make it easier to apply changes. This repository includes a C# .NET 10 client library which is built with Native AOT.
• 🔥 The network protocol has been adapted for Season 6 Episode 3 - there is probably still some work to do, but it connects to OpenMU and is playable. Additionally, the protocol has been extended so it's not standard anymore.
  • Damage, Exp etc. can exceed 16 bit now.
  • Improved item serialization
  • Improved appearance serialization
  • Added monster health status bar after attack
• 🔥 Significant changes from Qubit have been incorporated, such as
  • Rage Fighter class
  • Visual bug when Dark Lord walks with Raven
  • Item equipping with right mouse click
  • Glow for red, blue and black fenrir
  • Additional screen resolutions
• 🔥 Incorporated MU Helper UI and logic - there's some work to do but core functionality is usable
• Removed if-defs for Rage Fighter class as we are targeting Season 6, so Rage Fighter should always be included.
• Some minor bug fixes, e.g.:
  • Storm Crow item labels
  • Ancient set labels
• The code has been refactored. A lot of magic values have been replaced by enums and constants.

What needs to be done for Season 6:

• Lucky Items

How to build & run

Requirements

• Visual Studio Build Tools 2022 (minimum requirement - older versions won't work, newer versions are not tested)
• Visual Studio 2022 with the newest update, workloads for C++ and C#, Jetbrains Rider also works
• A compatible server: OpenMU

Building with CMake and MinGW-w64 (Linux)

The repository also contains a CMake setup to cross-compile the Windows client from Linux using a MinGW-w64 toolchain.

Prerequisites

• A working MinGW-w64 toolchain (for example i686-w64-mingw32-g++).
• A MinGW-w64 build of libjpeg-turbo which provides a libturbojpeg library (static or import library) on the library search path of your toolchain.
• Standard Windows / OpenGL libraries shipped with MinGW-w64 (e.g. opengl32, glu32, winmm, imm32, ws2_32, etc.).

Example build commands on Linux

From the repository root:

cmake -S . -B build-mingw \
  -DCMAKE_TOOLCHAIN_FILE=cmake/toolchains/mingw-w64-i686.cmake \
  -DCMAKE_BUILD_TYPE=Release
cmake --build build-mingw -j$(nproc)

If the linker reports cannot find -lturbojpeg, install a MinGW-w64 build of libjpeg-turbo (providing libturbojpeg.a / libturbojpeg.dll.a) or adjust the target_link_libraries entry in Source Main 5.2/CMakeLists.txt to match the name of the library available on your system.

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Step-by-Step Instructions:

Publishing the MUnique.Client.Library (Required for First Build)

Important: Because of the integrated C# code, you must publish the MUnique.Client.Library project before building the C++ client. A simple build is not enough - the DLL must be built with Native AOT and placed in the correct output folder.

This publish step only needs to be done once (unless you modify the C# networking code).

Option 1: Using Visual Studio (Recommended for Beginners)

1. Open the solution in Visual Studio 2026
2. In Solution Explorer, locate the MUnique.Client.Library project (under the ClientLibrary folder)
3. Right-click on MUnique.Client.Library
4. Select Publish...
5. If a publish profile exists, click Publish
   • If no profile exists:
     • Click Add a publish profile
     • Choose Folder as the target
     • Set the target location to:
       • For Debug: Source Main 5.2\Global Debug\
       • For Release: Source Main 5.2\Global Release\
     • Click Finish, then Publish
6. Wait for the publish to complete - you should see MUnique.Client.Library.dll (~ 5 MB) in your output folder
7. Now you can build the Main project normally

Option 2: Using Command Line

1. From the repository root, run:
   For Debug builds:

   dotnet publish ClientLibrary\MUnique.Client.Library.csproj -c Debug -r win-x86 -o "Source Main 5.2\Global Debug"

   For Release builds:

   dotnet publish ClientLibrary\MUnique.Client.Library.csproj -c Release -r win-x86 -o "Source Main 5.2\Global Release"

2. Wait for the publish to complete - you should see MUnique.Client.Library.dll in your output folder
3. Now you can build and run the Main project normally

Verifying the Publish

After publishing, verify that the following file exists:

• Debug: Source Main 5.2\Global Debug\MUnique.Client.Library.dll
• Release: Source Main 5.2\Global Release\MUnique.Client.Library.dll

If this file is missing, the C++ client will fail to link or run.

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Running the Client

It supports the common starting parameters /u and /p, example: main.exe connect /u192.168.0.20 /p55902. The OpenMU launcher will work as well. By default, it connects to localhost and port 44406. The client identifies itself with Version 2.04d and serial k1Pk2jcET48mxL3b.

Credits

• Webzen
• Louis
• Qubit (tuservermu.com.ve)
• Community members of RaGEZONE and tuservermu.com.ve for posting fixes
• Nitoy for the MU Helper