A MUD (originally Multi-User Dungeon, with later variants Multi-User Dimension and Multi-User Domain),[1][2] pronounced /ˈmʌd/, is a multiplayer real-time virtual world described primarily in text. MUDs combine elements of role-playing games, hack and slash, player versus player, interactive fiction, and online chat. 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.
Traditional MUDs implement a computer role-playing game set in a fantasy world populated by fictional races and monsters, with players being able to choose from a number of classes in order to gain specific skills or powers. The object of this sort of game is to slay monsters, explore a fantasy world, complete quests, go on adventures, create a story by roleplaying, and advance the created character. 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, history, and so on. Not all MUDs are games; some are designed for educational purposes, while others are purely chat environments, and the flexible nature of many MUD servers leads to their occasional use in areas ranging from computer science research to geoinformatics to medical informatics.[3][4][5] MUDs have attracted the interest of academic scholars from many fields, including communications, sociology, law, and economics.[6][7][8] At one time, there was interest from the United States military in using them for teleconferencing.[9]
Most MUDs are run as hobbies and are free to players; some may accept donations or allow players to purchase virtual items, while others charge a monthly subscription fee. MUDs can be accessed via standard telnet clients, or specialized MUD clients which are designed to improve the user experience. Numerous games are listed at various web portals, such as The Mud Connector.
The history of modern Massively Multiplayer Online Role-Playing Games (MMORPGs) like World of Warcraft, and related virtual world genres such as the social virtual worlds exemplified by Second Life, traces directly back to the MUD genre.[8][10] Indeed, before the invention of the term MMORPG, games of this style were simply called graphical MUDs. A number of influential MMORPG designers, such as Raph Koster, Brad McQuaid,[11] Matt Firor, Mark Jacobs, Brian Green,[12] and J. Todd Coleman, began as MUD developers and/or players