Multiverse and time travel RPGs
Roleplaying games that involve traveling through parallel dimensions or time are a relatively niche subgenre within the hobby. However, these themes are not obscure to the point of being unsupported – as the following list clearly attests.
While it might be the case that fiction about multiverses and fiction about time travel are two distinct subgenres, each with its own particular set of trappings and history, from the gaming perspective the two kinds of travel are functionally similar to the point that it makes sense to speak about them in tandem.
Whether you favor the terminology of alternate earths, dimensions, planes, or timelines, the overarching framework of such games remains the same: the characters routinely engage in hopping from one kind of setting to another. TV shows such as Sliders, Quantum Leap or Rick and Morty provide a template for this kind of adventures. Similar to their episodic structure, multiverse and time travel games effectively involve switching between multiple genres in the course of a single campaign.
Several games on the list present related, but slightly different scenarios, such as alien dimensions imposing themselves on Earth and transforming the familiar surroundings, or the discovery of a net of portals that allows fast travel through space.