Invisibility

Invisibility refers to objects and things not being seen in the game in some sense, especially:


 * The partial invisibility power-up from the Doom games.
 * The partial invisibility effect of the Doom games.
 * The translucency effect in Heretic and other games.
 * The invisibility power-up from Doom 3.
 * Transparent graphic resources representing invisible objects.
 * The property that makes things invisible (MF_NOSECTOR).