??? (Luigi's Mansion: Dark Moon)

??? is a dimension that appears in Luigi's Mansion: Dark Moon, where it acts as a "homeworld" for ghosts.

Overview
The dimension is accessed via paranormal portals, which can be found hidden in fake doors or various objects. Ghosts can freely transfer between the dimension and the Mushroom Kingdom by creating portals; larger portals can be created by more powerful ghosts. The dimension serves as the setting for the levels in the bonus challenges, Luigi's battle with the Tough Possessor, and the final battle with King Boo.

Demographics
??? is a home for many of the ghosts seen in the game.

Inhabitants

 * Greenies
 * Gold Greenies
 * Slammers
 * Hiders
 * Gobbers
 * Sneakers
 * Creepers

Zones

 * Bonus challenges - Mysterious areas containing challenges that reward anyone who completes them.
 * King Boo's Illusion - The area where Luigi fights King Boo.
 * An unnamed zone with a series of floating mansion rooms and corridors.

Trivia

 * If the player looks by a window in any floor of the ScareScraper, the same spiral background as in this dimension can be seen. This does not happen on the top floor, however.