Chobby, the ingame lobby.
There are multiple ways you can install Chobby.
Download chobby.exe from http://zero-k.info/lobby/chobby.exe and run it. It will download the newest version of Chobby as well as the required engine, and automatically start it. Should work under Windows and Linux.
Chobby is on rapid, under the "chobby" tag.
To download with pr-downloader use this command line:
pr-downloader chobby:test
You will need to obtain the appropriate engine and configure it manually.
The development version of Chobby can be obtained directly from here, and should be placed in your games subdirectory. Example (execute in your games folder):
git clone https://github.com/Spring-Chobby/Chobby.git Chobby.sdd
If you're using the wrapper, you don't need to read this. Just go ahead and run the executable.
Chobby is a Lua Menu and requires the newest engine. For exact version, see the engine tag in modinfo.lua (https://github.com/Spring-Chobby/Chobby/blob/master/modinfo.lua#L19).
For development version of Chobby (obtained from Github), you can launch Chobby by running spring --menu 'Chobby $VERSION' or by setting DefaultLuaMenu = Chobby $VERSION in your springsettings.cfg (https://springrts.com/wiki/Springsettings.cfg). Versions obtained from Github should follow the same procedure, but set the appropriate fixed version instead, e.g. Chobby test-1145-2d0ef36, instead of Chobby $VERSION.
If you are using chobby:test from rapid, you can specify rapid directly, instead of setting the version manually.
e.g. spring --menu 'rapid://chobby:test' and DefaultLuaMenu = rapid://chobby:test
See the wiki for more details, including Game Customization