[RPG] Rule Zero?


What is "Rule Zero" as it related to D&D 5e? I read How has D&D changed over time in its guidance to DMs as to when to extrapolate from written rules and when to improvise?, but it only went up to D&D Next.

Best Answer

Rule Zero, also known as GM fiat, is the common RPG rule that the GM has the ultimate say in all rules matters and can thus introduce new rules or exceptions to rules, or abolish old ones at their leisure. To put simply, it means the GM is like the god of the game. The Rule is commonly used to help ensure the written rules can always be changed to improve the realism, narrative, game balance or other appreciated qualities of the game. However, it may also hurt the game, if the GM applies the Rule in an arbitrary or careless manner.

It should be noted that while Rule Zero has decades of tradition behind it, it is not universally accepted. Many systems such as Apocalypse World have reasonably strict frameworks for the GM to operate inside and recommend house rules to be applied only through the whole group's consensus, although individual groups may still elect to allow Rule Zero.