Raiders of the Obsidian Sun
The Obsidian Maze is a freezing cold labyrinth made of smooth obsidian walls that goes on forever. There is no entrance or exit, only an unreachable center. There are ghosts and other spirits trapped in the dark walls, but they are only eerily noticeable out of the corner of your eye.
Of course, the Obsidian Maze is not real, you only saw it in your dreams…