Some role-playing games do not presuppose a particular world or setting. However, as a tool for creating a coherent imagined world, an implicit setting is used. Although not named, it is defined as having various broad characteristics and materials written about the game world assume other materials are also true.
Examples include the implicit setting of Dungeons & Dragons 3rd edition, a Greyhawk-like world; the implicit setting of Basic Dungeons & Dragons, which eventually formed the basis of Mystara; and the worlds of many superhero role-playing games, which often assume a world very similar to the Marvel or DC Comics universes.