A far less well-known meaning of this word follows:
Heretic is a first-person shooter video game created by Raven Software, published by Id Software, and distributed by GT Interactive[?] in 1994.
It uses a modified DOOM engine, which allows up- and down views.
In 1999, Raven published the source code of Heretic.
wikipedia.org dumped 2003-03-17 with terodump