Luminous

A bioluminescent underground landscape covers my entire field of vision: tiny mushrooms and plants glowing in blue, white, violet and pink. These enormous caves are the home of a people who are very concerned with rites of passage. The person going through the rite is locked in a cage, where they become involved in a battle against their fear of their dark twin. The dark twin is a creature wandering the caves. When the person in the cage has won over their fear, they are released from the cage, and set out to find and kill the dark twin.