Not sure if this is exactly what you're describing but I noticed the open-source Diablo engine DevilitionX has Zerotier built in to allow online multiplayer ses

Not sure if this is exactly what you're describing but I noticed the open-source Diablo engine DevilitionX has Zerotier built in to allow online multiplayer sessions. https://github.com/diasurgical/devilutionX/wiki/Multiplayer#zerotier https://github.com/diasurgical/devilutionX/wiki/Multiplayer#... I thought it was interesting way for an open-source game to provide a way to find other players without relying on paid dedicated servers.