MUSH, MUD, MUCK, MOO — what the words mean

Every one of these words names a family of server software, not a kind of game. That is the single most useful thing to know about them, and it is why "is this a MUSH or a MUD?" is so often answered badly: the honest answer is usually both, and the question you meant was about the culture.

MUD

The oldest term, and now the broadest. It began as Multi-User Dungeon — Bartle and Trubshaw's 1978 game — and by the mid-nineties was the umbrella word for every text-based multiplayer world.

Used narrowly, it means the DikuMUD and LPMud lines: servers built around levels, combat, equipment and an area file describing rooms a builder wrote in advance. If somebody says "I play a MUD" and means something specific, this is usually it.

The listing can show you each line on its own: the DikuMUD games and the LPMud games.

MUSH

Multi-User Shared Hallucination, from the TinyMUD line. The defining property is not the theme but the softcode: MUSH servers ship a programming language players use from inside the game, so a player with build permissions creates rooms, objects and behaviour without touching a source file or restarting anything.

That one design decision produced the culture. MUSHes tend to be sparse on automated systems and dense on human ones — staff-run plots, written scenes, application processes — because the people playing are also the people building.

PennMUSH, TinyMUSH, TinyMUX, RhostMUSH, CobraMUSH and AresMUSH are all in this line and none of them says so: MSSP has no MUSH value to publish, and all but PennMUSH publish no MSSP whatsoever. Grouping them is therefore something we do rather than something we read, which is why the MUSH games is marked derived wherever it appears.

MUCK

A TinyMUD descendant like MUSH, with its own softcode (MUF, a Forth-like language) and a strong tradition of social and furry-fandom worlds. Technically close to MUSH; culturally distinct enough that people who play both would not describe them as the same thing — the MUCK games.

MOO

MUD, Object-Oriented. The purest expression of the "the game edits itself" idea: nearly everything in a MOO is written in the MOO programming language by the people using it, from inside. LambdaMOO is the ancestor, and MOOs have historically been as popular in education and research as in games. The MOO games.

So what should you actually ask?

Three questions do more work than the four-letter word:

1. Is there combat, and is it automated? This separates the Diku/LP line from the TinyMUD line more reliably than any name.
2. Who builds? Staff-only, or anyone with a build bit?
3. Is play scheduled or ambient? Appointment-based scenes and posed roleplay, or log in and go?

The listing on this site can answer part of the first question for you: the codebase we measured for a game tells you which tradition its server comes from, and the lineage facet is that answer made filterable. It cannot tell you the culture, and this page will not pretend otherwise.

One caution about that facet, since this page is where somebody will meet it. The codebase is measured and the lineage is not: it is our grouping of what a game told us, carried under its own label — derived — beside measured and declared. Where a codebase has no uncontested parent it is left out of every lineage rather than filed under the nearest one, and several of those games agree with us in their own words, publishing FAMILY Custom.