Private Server Emulators Explained: Cores, Clients and Databases

An emulator is a stand-in for the publisher's servers

When people say a private server runs on an emulator, they mean the server software is a re-creation. It listens to the official client, understands its messages and answers them the way the original service would. Wikipedia defines an emulator in general as 'hardware or software that enables one computer system (called the host) to behave like another computer system (called the guest).' A game server emulator applies that idea to an online service.

This differs from the console emulators you may know. A console emulator runs old games locally; a server emulator runs the other side of an online connection. Our private servers directory lists servers by game, and the glossary defines the words used below.

The parts of a server emulator

Almost every emulator project splits into the same pieces. Knowing them helps you ask operators sensible questions about stability and updates.

The core and the database are separate on purpose. In the World of Warcraft emulation scene, many servers share an open-source core and differ mainly in database content, which is why two servers on the same version can behave differently. Wikipedia notes that private servers are often reverse-engineered 'using incomplete information', so missing mechanics are normal even on good projects.

Real emulator projects

Open-source emulators document themselves, which makes them the easiest to verify. The table summarises what each project says on its own repository or site.

Licenses matter to operators. The GPL licenses used by TrinityCore, CMaNGOS and rAthena carry conditions on sharing modified code, whereas bancho.py is MIT licensed, which is more permissive. The licenses cover the server code only. They say nothing about the publisher's client or assets, and those are a separate matter from the open-source terms.

Emulator versus custom server files

Not every game has an open-source emulator. Games such as MU Online, Silkroad Online, Metin2 and Aion usually run on server files that circulate privately, are modified by each operator, and rarely have public documentation. That has consequences for players.

The distinction is visible in our hubs. Ragnarok and osu! servers often name their core, while MU Online, Silkroad and Metin2 servers tend to describe features and rates instead. Neither is automatically better, but the first group is easier to evaluate.

How the client finds the server

The client does not know it is talking to an emulator. Most clients read a server address from a config file, a launcher or a patched executable, and from then on they exchange the same kinds of messages they would with the official service. That is also why client and server versions must match exactly: if the client expects a message the core does not understand, the connection fails or the game behaves oddly.

Our segment pages sort servers by these labels, for instance MU Season 6 and WoW Wrath of the Lich King. When a server says 'latest', ask which build it means.

Common problems with emulated servers

• Missing or inaccurate mechanics, since emulators are built from incomplete information.
• Exploits that duplicate items or gold, which can wreck an economy overnight.
• Crashes under load when the core was written for small populations.
• Abandoned projects where the lead developer leaves and no one can patch.
• Custom launchers that bundle more than a patcher.

What to ask an operator

1. 1

   Which core and version do you run?

   A named, maintained core is a good sign.

2. 2

   Who maintains it?

   One developer or a team? How fast are bug fixes?

3. 3

   Do you publish patch notes?

   Regular notes show active work.

4. 4

   How is the database backed up?

   Backups decide what survives a crash.

5. 5

   What does the launcher do?

   It should only patch and start the client. See the safety guide.

Good operators answer these questions without fuss. Evasive answers on the core, the launcher or the backup routine are worth noting, especially if the server also asks for donations. A project that is open about its stack, such as one that links its repository or names its core and version in the Discord, is easier to trust and easier to compare against alternatives.

MaNGOS announced

~Aug 2005

Per its repository page

PvPGN official development stalled

2011

Forks continue

TrinityCore 3.3.5 client build

12340

3.3.5a, from its README

For more on what to expect before you join, see how to join a private server and the selection guide. If you are interested in running your own, start from the community-building guide, and use each hub to study active examples.