Dark Deception: Unchecked Limitations/Hidden Nightmares

Hidden Nightmares are bonus levels in Dark Deception: Unchecked Limitations. They are extra-difficult levels that are completely optional in the story mode but are required in order to obtain Cosmic upgrades. There is at least one Hidden Nightmare in every Chapter. The Hidden Nightmares can be played at any difficulty except for easy mode. Obtaining an A rank or S rank in all levels within a single chapter will automatically unlock the Hidden Nightmares present within that Chapter.

Trivia

 * Originally, Wreckage Warehouse and Melodramatic Museum were going to be the only levels in Dark Deception: Unchecked Limitations that doesn't have alliteration in the title, much like Monkey Business from the base game. The original names for these are:
 * "Wary of Danger" (Wreckage Warehouse)
 * "The Art of War" (Melodramatic Museum)
 * In this version of Dark Deception, when a nightmare collapses it can be rebuilt.