Open source. A world to build on.

An open server for
Ragnarok Online 3.

RO3Emu is a server emulator for the RO3 PC client, written in C# and .NET 10. Explore how an MMORPG works, from its first protocol message to its guild sieges.

Explore on GitHub Build the server

GNU GPL v3.0 · Client research and implementation notes included.

THE WORLD, SERVER SIDE01 / PROTOCOL MAP

Architecture illustration · Read the design

LANGUAGE & RUNTIMEC# / .NET 10

LICENSEGNU GPL v3.0

CLIENTRagnarok Online 3 PC

GET INVOLVEDCode, research & documentation

INSIDE RO3EMU

Follow a message.
Understand a world.

The repository brings protocol research, gameplay systems and server tools together. Client evidence is cited in the code and docs; choices the client cannot establish are marked (inferred).

World & combat

Maps, NPCs, visibility, monsters, skills, buffs and character progression.

Trace the world protocol

People & economies

Parties, chat, mail, trade, stalls, auctions and guild systems.

Explore trade and stalls

Instances & territory

Dungeons, scripted scenes, activities, territory wars and castle siege systems.

Read the territory design

Tools for the work

Protocol bots, load scenarios, data exporters, client patch tools and a launcher.

Find your starting point

FROM READING TO BUILDING

Start with the code.

With the .NET 10 SDK, you can clone and build the server without a game client.

For a playable world, bring your own RO3 PC client and export its data. The setup guide covers the additional tools, data export and client configuration.

Follow the complete setup guide

BUILD THE SERVER

git clone https://github.com/aethai/ro3emu-server.git
cd ro3emu-server
dotnet build src/Ro3Emu.Server -c Release

Builds server code. Playing requires exported client data.

MAKE YOUR FIRST CONTRIBUTION

Bring curiosity.
Leave something better.

A clearer setup step, a reproducible bug report or a well-supported protocol finding can make the project easier for everyone who follows.

Read the contribution guide

Reproduce a problem

Share the build, exact steps and observed result.

Investigate the protocol

Connect client evidence to a specific server behavior.

Improve the next first run

Test instructions and document what was missing.

Before you begin

Which game and client does RO3Emu target?

The Ragnarok Online 3 PC client, also called RO3 and ROO_PC in the setup instructions. This project targets that client's protocol. For supported setup details, start with the README.

What is included in the repository?

Server and tool source code, protocol definitions, documentation and tests. The game client, exported game data and game artwork are not included. A playable setup requires your own client and the data export described in the guide.

Can I contribute without the game client?

Yes. Start with documentation, the server build or client-independent tooling. Some end-to-end tests and all in-game validation require exported client data. The contribution guide explains the distinction.

Is this an official Ragnarok project?

No. RO3Emu is an independent research and interoperability project, unaffiliated with Gravity or any Ragnarok publisher. Ragnarok Online is a trademark of Gravity Co., Ltd.