Room

Rooms and doors are the building blocks of metarooms and worlds. A room is a quadrilateral space usually taking the form of a rectangle with straight sides, although in C2 they may have floors of varying height and in C3/DS the top and bottom may be raised or lowered independently of one another.

Despite the name, areas that correspond to one visually contiguous space in the games after C1 - such as the incubator area in C2, the lower levels of the C3 Jungle Terrarium or the lower Norn Meso in DS - are normally composed of multiple rooms linked together. This allows for more natural flow of CAs and provides much more detail and variability in shape than is possible for a single large room, which can have only four sides. Regions in which neither is a factor, such as the C3 Crypt, are usually composed of a single room.

If rooms in C1/C2 are improperly defined, it can result in Black Holes forming.