[RPG] “GM/DM Fiat?”


While I explore this site, I occasionally see the phrase "GM fiat" (or "DM fiat", for D&D questions and answers), but I don't know the exact meaning of that. I want to know the meaning of that terminology.

Best Answer

In a large number of RPGs the GM is positioned as the controller of the world, its NPC inhabitants, the items in the world, and their essential natures. They are also often positioned as the final arbiter of rules and thus hold considerable authority. It tends to be these games in which “GM fiat” is a thing. Hopefully a GM imbued with such power will remember: with great power comes great responsibility.

With that said, a fiat is defined as:

  1. an authoritative decree, sanction, or order
  2. (irrelevant)
  3. an arbitrary decree or pronouncement, especially by a person or group of persons having absolute authority to enforce it

So a GM fiat is when the GM says something is the case—because the game or environment gives the GM authority to do this—and simply by doing so it becomes the case.

A GM fiat is produced independently by the GM. It is separate to decisions made by the group as a whole: a GM can declare a house rule as a GM fiat, but that's different to the group producing a house rule together. Implicitly the GM is not generally expected to have to justify or explain their fiat; they can simply decree it and it is so.

Because GM fiats are arbitrary and can involve major changes (like the changing of the rules themselves) the motto of “with great power comes great responsibility” is massively relevant. These changes could make the game more fun or extremely un-fun for players. Sometimes GM fiat gets wielded like a hammer so that whatever the GM wants, happens. Our hobby is fundamentally about people having a conversation for a while to collaborate and create fun for themselves and each other; many changes that materially affect players outside the course of simply running the game world will be better handled by discussion, buy-in, and consent rather than fiat.

Some examples of usage of GM fiat

  • Create your own fluff for in-game races, civilisations, etc, which may either add to or replace lore from the books.
  • Create new material in the universe, such as:
    • New items which don't exist in the game's rulebooks.
    • New planes, gods, and so on. A fellow member of this site once played in a game where all bags of holding lead to their own demiplane, with a Demigod assigned to guard all such demiplanes.
    • In D&D, create a Freezing Hands spell as a cold equivalent of the actually-in-the-books Burning Hands, and give it to one of your players or NPCs.
  • Make a declaration about how a certain rule works, especially for clearing up ambiguities.
  • Make rulings where there is no clear rule.
  • Declare that something simply happens when there is no clear justification for it.
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