LiveJournal (for announcements): http://nasgarath.livejournal.com/
Telnet address: riva.silvren.com 7777
RivaMUSH is an old game (originally created in 1994) based on the novels by David Eddings (The Belgariad and The Malloreon). It went on hiatus in 1999 then re-opened in 2005 with a mostly new staff.
For those unfamiliar with the books, it is a world of fantasy where magic and warriors reign, somewhat based on elements of our own history (the Tolnedran Empire, for instance, is modelled after the Roman Empire.) Having read the novels is not required, however, unless you wish to play a feature.
When the game re-opened in 2005 it started over from scratch, picking up five years after the end of the books. Until the playerbase grows, the RP will be focused in Tolnedra.
RivaMUSH is a strongly RP-driven game which relies on the Consent Rule and, well, common sense.
The codebase used is RhostMUSH.
This MUD appeared to be ACTIVE at last check.