I’m not sure that’s possible with multiplayer games, at least the central server part. They could release the central server code as an open source project… that would be very useful. But MMOs need that central communication to even work. I mean I guess you could engineer some sort of peer to peer but I’ve dealt with weird firewall rules in various DCs I’ve had servers located in or god forbid the lack of incoming connectivity in peoples homes. Outbound traffic is usually fairly unrestricted so a publicly available server is the way to go architecturally.