If you have, then you've probably been to a liminal space. On the Internet, that usually refers to empty rooms, corridors, ...

The scenes they contain are ordinary: a corridor of unmarked doors stretching into blackness; a slide leading to an empty, windowless ball pit; an indoor pool illuminated by an unearthly glow.

British anthropologist Victor Turner's 1964 paper Betwixt and Between describes the liminal phase of ritual as a departure from the ordinary rules of time, space and social hierarchy ...