Host a custom MMO on your own LAN. The Remnants project seeks to provide a framework in which players can enjoy a persistent world without being held hostage by proprietary pay servers. Can a few new tools extend the MUD dimension?
An attempt to fill in the void of affordable/open-source MMO engines written in C#. Newly updated using XNA, Lidgren and a custom physics engine. Checkout the ForgeRealm project which we have now merged with.