Adept Play
(Full title: The Book of Madness: Whispers Without, Chaos Within) A supplement for Mage: The Ascension by Bill Bridges, Phil Brucato, and others; published by White Wolf Studio in 1995.
It is crazy how common and how widely-developed craziness is, in role-playing. As much as world-building, as much as combat options, as much as magic systems, this is a definite feature of the hobby with its own schools and aims. It is clearly a primary path toward characterization, character development, player agency (through its managed…