Liminal rifts are doorways to other worlds opened by the light of the Moon. These rifts are often located in “liminal" spaces, areas with associations with a boundary or a transition, like a bus station, a waiting room, or a parking lot. In these areas the fabric of reality in the City sometimes weakens, creating a pathway from the City into another world.
The worlds beyond a rift are highly variable in size, appearance, and population, but they will always be familiar to whoever first discovered the rift. This can range from a vague resemblance to a childhood home, populated by unresponsive shadows, to stepping out into the streets of a lively city plucked from a story. Residents can freely enter and leave a rift, and entities within in the rift may pass into the city if they can find the opening.
Liminal rifts are temporary, lasting a night before they fade with the rising sun. Once a rift closes, any outsiders inside the rift are returned to their entry point in the City, while any entities that left the rift will vanish from within the City. However, objects and effects acquired while in a rift will persist.
Mechanically, a liminal rift is a way to explore worlds beyond the City. More or less anything goes on what can be explored, including worlds from other media or original settings.
The temporary nature of rifts means that they only last as long as a thread - however, you may visit the same world multiple times through different rifts. The continuity of these rifts is up to the people visiting them, and does not have to be consistent between visits or players.
As stated above, you may take items or acquire upgrades from a rift - however, please use your best judgement when doing so.