A setting, campaign setting, fictional universe, or milieu is the time and place in which the fiction of a campaign or other role-playing game is supposed to happen. To the extent that setting information is understood and agreed by a group's players, it is part of that group's system because players (and, perhaps more importantly, the GM) will be influenced by their understanding and expectations of the setting to assess fictional positioning and make decisions that impact the events in the game world.
Classifications of settings
By scope and scale
The amount and scope of established information about a setting, its lore, varies considerably between games. This particularly depends on how large an area the setting covers (as small as a single building or neighbourhood, to as large as an entire multiverse), and how different it is from the real world. Some settings will intentionally include only a small amount of information, allowing more to be established during play.
Some settings take place on something like the real world, a fictionalised (modern or historical) Earth, and include only information that explains how the setting differs from reality. Sometimes there are no significant differences in how this fictionalised Earth works compared to the real one, except for the original characters and situations that appear in it (e.g. the fictionalised real worlds of James Bond 007 or Leverage or World Wide Wrestling).
In other fictionalised world, these differences to reality may be significant, perhaps by the introduction of fantasy or science fiction elements, such as the widespread existence of supernatural creatures in the World of Darkness. Even in this case, however, anything not described in the lore of the setting can usually be considered to resemble the real world.
Other settings have no connection to the real world (though they may still resemble it in places for the sake of verisimilitude), and the settings are wholly imagined worlds. Fantasy settings are commonly create whole fantasy worlds with original places, creatures, cultures and metaphysical laws (for example). For example, Oerth is the imaginary world of the Greyhawk setting for Dungeons & Dragons. (This was the original distinction between high fantasy, set in a fantasy world, and low fantasy, set in an alternate real world with fantasy intruding on it, although the terms are sometimes used differently now.)
The largest scale of a setting is to include multiple worlds in a sort of universe or multiverse. In a science fiction setting, this may be a galaxy with multiple alien worlds (even including a fictionalised Earth among them, since science fiction is a form of speculative fiction that purports to imagine what is possible), such as the planet Vulcan in Star Trek. In a fantasy setting, the wider setting might be a collection of planes that can be accessed magically.
By style and intended usage
Groups may either create their own campaign settings (called homebrew settings) or use a (fully or partially) pre-generated setting. Most published games include at least one sort of pre-generated setting, which may be from the following types:
- integrated setting, when system mechanics are so connected to the setting that no other setting can be used without extensive hacking;
- default setting, when one specific setting is provided by the game rules, but the game could support others;
- alternate setting, a setting that can be used instead of a game's default setting;
- implicit setting, when no setting information is provided explicitly but some facts about the setting can be determined from the game's rules;
- example setting, generally found in generic role-playing games (in which groups are expected to use their own settings) by providing an example of a setting that is used to explain the rules but never intended to be used in an actual game.
By relationship to canon
Another distinction in settings is in their relationship to canon. Settings generally assume that anything described in game texts as existing in the setting will exist in any campaigns that take place in that setting, with some leeway for groups to customise it. Different games may assume a different level of adherence to canon. At its most stringent, canon not only describes the current situation in a setting but also its ongoing narrative that gaming groups are expected to follow, which is called a metaplot. At the other end, some games use settings that reject a consistent, canonical version, which are called anti-canon.
Some settings also exist independently of any games, for example settings from established franchises and intellectual property (e.g. Star Wars or the DC Universe). These may be used in officially licensed games as default, alternate or integrated settings, or homebrewed by players into other game systems. Sometime, setting books are published for RPG consumers that include settings that can be used in multiple game systems.