Neil Newell, an avid MUD1 player, started programming his own MUD called SHADES during Christmas 1985, because MUD1 was closed down during the holidays.
Starting out as a hobby, SHADES became accessible in the UK as a commercial MUD via British Telecom's Prestel and Micronet networks.
Many MUDs were fashioned around the dice-rolling rules of the Dungeons & Dragons series of games.
Such fantasy settings for MUDs are common, while many others have science fiction settings or are based on popular books, movies, animations, periods of history, worlds populated by anthropomorphic animals, and so on.
Scepter supported 10 to 16 simultaneous users, typically connecting in by modem.
It was one of the first commercial MUDs; franchises were sold to a number of locations.
The history of modern massively multiplayer online role-playing games (MMORPGs) like Ever Quest and Ultima Online, and related virtual world genres such as the social virtual worlds exemplified by Second Life, can be traced directly back to the MUD genre.
Colossal Cave Adventure, created in 1975 by Will Crowther on a DEC PDP-10 computer, was the first widely used adventure game.
When one of the two programmers left Compu Net, the remaining programmer, Alan Lenton, decided to rewrite the game from scratch and named it Federation II (at the time no Federation I existed). Federation II was later picked up by AOL, where it became known simply as "Federation: Adult Space Fantasy".
Players can read or view descriptions of rooms, objects, other players, non-player characters, and actions performed in the virtual world.
Players typically interact with each other and the world by typing commands that resemble a natural language.
Numerous graphical MUDs were created on the PLATO system at the University of Illinois and other American universities that used PLATO, beginning in 1975.
Among them were "pedit5", "oubliette", "moria", "avathar", "krozair", "dungeon", "dnd", "crypt", and "drygulch".
MUDs can be accessed via standard telnet clients, or specialized MUD clients which are designed to improve the user experience.