MUnique OpenMU Project

Measure first

How OpenMU’s startup got faster: a measurement tool first, then compiled EF Core models and generated plugin proxies - and one line of SQL which was worth more than all of them.

The Attribute System, five years later

Five years after the attribute system post: the whole Season 6 skill set went through it, and the core barely changed. A look at what that took.

Bots that play your server

Server-side bots which hunt, group up and log in and out over the day - no client, no packets. How they work, what they cost, and what a thousand of them found in the engine.

The MU Online protocol, explained

A TCP socket, a stream of bytes, and nobody who wrote down what they mean. A tour of the MU Online wire format: framing, the three things called encryption, and what we changed.

A .NET library inside the game client

The client's network code is C# now - a Native AOT library loaded into a 20-year-old C++ game's own process, with no runtime installed. Here's how it works, and why it needed .NET 9 to be possible.

Why the server project needed a client

For ten years the client was the one part of the system we couldn't change. This is what that cost in bytes - and what opened up once one end was finally ours.

Photo by Aron Visuals / Unsplash

Recap of 2023 - 2026

Almost four years without a post - but not without work. A recap of what happened to OpenMU since 2022, and of the project I never mentioned here: my fork of the MU Online client sources.

Optimized pathfinding

Optimized pathfinding

After some tests of the community, we found that many instances of monsters on a map will cause a lot of memory usage. As I found out, the root of the cause was how we do the pathfinding for the monsters. Because of that, I took this as a challenge

The power of the Attribute System

The power of the Attribute System

I want to show a nice powerful feature of the OpenMU Project - the Attribute System.

Project Status - Easter 2020

Project Status - Easter 2020

I want to give a short status update on the OpenMU project.

Demo Console Client for MU Online

Demo Console Client for MU Online

For a test of the new nuget packages of MUnique.OpenMU.Network.Packets I wrote a small demo client. You can find the source code here: https://github.com/sven-n/MuConsoleTestClient It encapsulates most of the packet creation and parsing for you, so you don't have to

Recap of 2019

In this post I want to recap what was accomplished in 2019 and what will come next in 2020.

Generating message structs by data

Generating message structs by data

In this post I want to explain how I'm planning to generate ref structs in OpenMU and how this fits into the big picture.

Handling packet structures in .NET - a new way?

Handling packet structures in .NET - a new way?

Parsing and serializing network packets in .NET in a safe, performant and elegant way can be quite tricky. C# ref structs might be the answer.

SimpleModulus revisited

Recently, I was working on getting game client version 0.75 to work with OpenMU. One big obstacle was the SimpleModulus encryption which was somehow different in the earlier versions of MU Online. You can find an analysis of it here. According to a change log in a leaked 0.

Migrated AdminPanel to Redux and TypeScript

Migrated AdminPanel to Redux and TypeScript

I finally finished the migration of the AdminPanel from JS/JSX to TS/TSX and fluxxor to Redux. I want to show you a short summary of pitfalls which I encountered and how I solved them. Not using npm When working with JavaScript you almost can't get around

Understanding the relationship between react, redux and react-redux

react and redux are basically independent libraries. You can use react without redux and redux without react. What glues both together is the react-redux library. I don't want to write a full blown tutorial about react and redux, so I'll keep it short. Disclaimer: I&

On item duplication exploits and how to prevent them

Hello, first of all, if you're Webzen or a private MU Online server owner or developer, don't take this post as a threat. These item duplication examples which I will describe are known to me since many years. As you might imagine a lot of other

About game server architecture patterns

Hey there, I found a really nice blog about game server architectures: https://gameserverarchitecture.com If I would categorize the original MU Online game server into one of the mentioned architecture patterns, it's probably mostly the monolithic one, with some slight signs of the map centric pattern in

Loading complex data with PostgreSQL JSON functions

Loading complex data with PostgreSQL JSON functions

Problem With an extension of initialization data, where I added definitions of NPCs and Monsters and their spawn points to about 10 game maps, I noticed that the time to start the server went up dramatically - from ~13 seconds to over 1 minute. The reason was, that my strategy to

MUnique OpenMU Network Analyzer

Hey people, today I release a little tool to analyze network traffic between server and client which use the mu protocol. The cool thing is, the packet structures are defined in xml files, so it can be extended like you wish. Changes on this xml files also work on-the-

A closer look at the MU Online packet encryption

in the past days I wondered why some parts of the encryption and decryption keys for the network packet encryption (aka SimpleModulus) are actually the same. So I tried to dig a bit in the SimpleModulus algorithm and the usage of these keys. Lets see how this keys (e.g.

ChatServer v.0.1.4

Today I decided to add a new release for the ChatServer (ExDbConnector). With the feedback of a RaGEZONE user we managed to get it actually working with a real season 6 game server :) It's always a satisfaction when you get something working, especially if you're the

Naming of the OpenMU Project

There are only two hard things in Computer Science: cache invalidation and naming things. -- Phil Karlton Some of you might have noticed, that there is a private MU Online Server "OpenMu" and maybe several other (dead) projects with a similar naming. I want to clarify that my "

Chat Server v0.1.0-alpha

Today I release a spin-off project of OpenMU. It uses the ChatServer and it's dependencies of OpenMU, but additionally I wrote an adapter to connect it to a non-OpenMU ExDB-Server. So you can use this as a complete replacement of the original Webzen ChatServer. A