Cleanroom Relauncher

Relaunches a Forge 1.12.2 instance with Cleanroom.

Client only at the moment.

• Relaunch Now installs the latest Cleanroom and a compatible Java runtime.
• Advanced Settings lets you pick a version, a Java install, and JVM flags.
• Settings can still be changed later in-game via the config menu.

Installation Notes

• Keep the ! at the start of the filename so Forge loads the mod first.
• Cleanroom also expects Fugue to fix some of the old Forge mods.
  • And Scalar for mods that used to depend on Scala 2 components.
• Releases are taken from GitHub, with CleanroomMC Maven as a fallback.
• Downloads and provisioned Java are cached under ~/.cleanroom/ (relauncher/ and java/).
  • Change that parent directory with -Dcleanroom.homeDir=<path>.

Distribution via Modpacks

• Put the jar in mods/. Players see the setup window on first launch.
  • To skip that window, ship a filled-in config/relauncher.json. Run the pack once locally and copy the file.
  • Automatic Java setup is the usual choice for distribution.
• If the instance is already running Cleanroom, nothing is relaunched.

Config

Written to config/relauncher.json:

• Cleanroom Version
• Automatic Java (version + vendor, default Java 25 / Zulu) or a path to an executable
• Extra JVM Arguments
• Whether to check for newer Cleanroom releases
• Cleanups

Links

• CurseForge
• Modrinth
• Cleanroom