Arkona

uc-online

I'll introduce UnionCrax's original uc-online launcher and show you how to configure it for a compatible game. This is the launcher guide, not the separate uc-online2 project.

Choose the right build

uc-online does not add multiplayer to a game that lacks it. Players need compatible game versions and configurations. The author also links a separate uc-online2 project; its setup is not interchangeable with this one.

  1. Download a Windows x32 or x64 build matching the game's process. Back up any files that will be replaced.
  2. For the nosteamworks package, keep the game's Steam API DLL: the launcher will load it from SteamApiDLLPath. For the package with its own Steam API, extract the launcher into a separate directory and point it at the game executable, avoiding a DLL collision.

Configure config.ini

  1. Create config.ini next to the launcher. Its first run may generate only AppId, so add the other required fields yourself.
  2. Set GameExecutable to the real game executable, with a relative path from the launcher folder. Use GameArguments only for arguments required by that game.
  3. For nosteamworks, SteamApiDLLPath is the directory containing steam_api.dll or steam_api64.dll, not the DLL filename. Set SteamAppIdFile to the steam_appid.txt path used by the setup; its contents must agree with AppId.
AppId = 480
GameExecutable = .\gmod.exe
GameArguments = -steam -game garrysmod
SteamApiDLLPath = .\bin
SteamAppIdFile = steam_appid.txt
EnableLogging = false
LogFile = uc-online.log

This is the author's Garry's Mod example, not a configuration to paste unchanged into every game. App ID 480 is Spacewar; seeing that name in Steam only confirms the shared ID is in use.

Launch and troubleshoot

  1. Start Steam and sign in. Run uc-online.exe or uc-online64.exe for the selected architecture, then use the game's compatible lobby or invitation workflow.
  2. If the game does not start, check the executable path, DLL directory and architecture. Set EnableLogging = true temporarily and read uc-online.log. To remove the setup, delete only the launcher files you added and restore the files you backed up.