XMud is an extensible MUD, inspired by LambdaMOO and LPMUD. It allows users to extend the system at run-time by creating new objects. Objects are Java classes that follow certain rules with respect to manipulating the state. It was designed with with scalability in mind; the system may be composed of N servers and M clients. Each server is nothing more that a state manager that controls reading, writing, and locking state elements. Methods are executed at the client level and generate state change requests that are sent to the server.