Abnormalities (Hangul: 환상체, Hwansangche) are entities within Project Moon's setting that manifest from the mind of humans, and, as such, reflect an aspect of desires or fears of people.

They are a central focus of Lobotomy Corporation as a means of acquiring energy to advance the game, and are also prominent in Library of Ruina as allegories for aspects of the setting and the game's main characters. In Limbus Company they are boss fights within the game's Cantos (chapters), some of which are variants from alternate dimensions.