The next AUM will include a functional multiplayer code, too. It is the second and highly improved version of the first iteration from last AUM, which in turn was based on the Multiplayer tip on the GStudio wiki (the tutorial presented here by EpsiloN seems to be based on either the wiki post or the version from the last AUM, so you may want to start reading there first).

"Falls das Resultat nicht einfach nur dermassen gut aussieht, sollten Sie nochmal von vorn anfangen..." - Manual

Check out my new game: Pogostuck: Rage With Your Friends