ErlyMUD is a rather minimalistic MUD server, written in Erlang and making use of the excellent OTP libraries. The aim is to have solid support for exploration and roleplaying, within a highly fault-tolerant environment where system crashes or reboots are more of an exotic curiosity than a commonplace thing.
Cancan is a text-based, interactive utility similar to telnet, but with a number of extensions useful for MUD playing. Another use might be to provide line editing, aliases, etc., for those services that have a simple telnet interface. Cancan features aliases, actions, key bindings, text highlighting, substitutions, and line editing with history and completion.
Gamma Low is a multi-player RTS in which two opposing teams of light-based lifeforms fight for the dominance over a cellular system in match style. The players in each team are split into different classes (strategist, tacticians, workers/attackers/supporters) and have to conquer all enemy cells in order to win. They do so by harvesting resources, building structures, researching technologies, creating deadly viruses, and fighting harsh battles.