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Run from source

Use this way if you want to develop or debug OpenMU. It works on Windows, Linux and macOS. Where the steps differ per operating system, both variants are shown.

Requirements​

  • Windows 10 or higher, a current Linux distribution, or macOS
  • PostgreSQL installed, or Docker to run it in a container (see step 3)
  • An IDE: Visual Studio 2026 on Windows (with the workloads for ASP.NET Web development and .NET Desktop development), Rider, or VS Code with the C# extension. Plain command line with the SDK below works as well. Please keep your tools up to date to prevent issues.
  • .NET SDK 10 (already included in Visual Studio 2026) 
    winget install Microsoft.DotNet.SDK.10
    On Linux and macOS, install it through your package manager or the installer from the download page linked above.
  • NodeJS 16+ 
    winget install OpenJS.NodeJS.LTS
    On Linux, install it through your package manager (for example sudo apt install nodejs) or from the download page linked above.
  • This repository cloned

Steps​

  1. Open the OpenMU solution in your IDE.

  2. Restore the NuGet packages: Visual Studio offers Restore NuGet Packages on right click of the solution, or run this from the repository root:

    dotnet restore

  3. Configure the postgres admin credentials (pick one option):

    • Recommended: environment variables. Set DB_ADMIN_USER and DB_ADMIN_PW to the user/password of your postgres superuser account (leave DB_HOST unset to use localhost). Only the admin credentials need to be correct. The server creates the database schemas and the other roles (config, account, friend, guild) itself.

      export DB_ADMIN_USER=postgres
      export DB_ADMIN_PW='s3cret'

      On Windows (PowerShell) instead:

      $env:DB_ADMIN_USER='postgres'
      $env:DB_ADMIN_PW='s3cret'

      When the variables are not set, the defaults (postgres / admin) apply. Avoid ; in the password, since it separates values in connection strings.

    • Alternative: edit src/Persistence/EntityFramework/ConnectionSettings.xml so that the connection strings are correct. Only the user/password of the first and second connection string need to be correct. The server will try to create the other roles specified by the settings.

    Whichever option you picked, if you run postgres in Docker instead of installing it, start it with a matching user, password and database name (openmu):

    docker run -d --name openmu-db \
      -e POSTGRES_USER=postgres -e POSTGRES_DB=openmu \
      -e POSTGRES_PASSWORD='s3cret' \
      -p 5432:5432 postgres

  4. Build the solution, in your IDE or from the repository root with:

    dotnet build src/MUnique.OpenMU.sln

  5. Start MUnique.OpenMU.Startup. The environment variables from step 3 must be set wherever you start it (same terminal, or your Debug launch profile). From a terminal:

    dotnet run --project src/Startup/MUnique.OpenMU.Startup.csproj -- -autostart

    (The -- passes -autostart to the server instead of to dotnet.)

    • If required, it creates the database schemas and the required roles, and gives permissions to those roles.
    • Optional: you can reinitialize the database by adding the -reinit parameter.

  6. When the admin panel is initialized, go to http://localhost/. You should see three game servers, the chat server and two connect servers. Start the connect servers and at least one game server — see Servers.

  7. Connect to the server with the game client, see Game client.

Updating to a newer master

If you update to a newer state of the master branch, it is possible that the database and the configuration have to be updated. You find those updates in the admin panel, see Configuration updates and Setup.

Helpful optional steps​

Auto start​

If you don't want to start each server listener manually after starting the process, you can either

  • activate Auto Start in the admin panel at Configuration → System, or
  • use the start parameter -autostart.

IP resolving​

If you encounter disconnects after selecting a server, it is most likely a wrong setting for the IP resolver. You can change it in the admin panel at Configuration → System.

You may also change the setting by start parameters or environment variables, but this is only recommended for experienced users — see Startup parameters.

Changing the game version​

If you want to play a version other than Season 6, you can initialize the database with another game version on the Setup page of the admin panel.

In-memory mode​

With the -demo parameter, the server uses in-memory repositories instead of an external database and initializes the data at each start. This is handy for a quick test, but player progress is not saved.

Building from the command line​

dotnet publish src/Startup/MUnique.OpenMU.Startup.csproj --configuration Release

The tests are run with:

dotnet test