Basically, these techniques are merely designed to make it easier for the individual to achieve the out-of-body state when his brainwave pattern and personal energy levels have reached a point that he is in apparent harmony with his surrounding electromagnetic environment such that he feels that he has reached the threshhold where separation is a possibility.
The Adventure Family Tree (mipmip.org)An incomplete chronicle of Crowther and Woods’ Colossal Cave Adventure, the “fons et origo of interactive fiction, and one of the hallowed artifacts” of computer gaming history.