The original edition of Heretic was only available through shareware registration (i.e. mail order) and contains three episodes. A retail edition, distributed by GT Interactive, was titled Heretic: Shadow of the Serpent Riders and features two additional episodes: The Ossuary, which takes the player to the shattered remains of a world conquered by the Serpent Riders many centuries ago, and The Stagnant Demesne, where the player enters D'Sparil's birthplace. A free content patch was downloadable from Raven's website to update the original Heretic to match Shadow of the Serpent Riders.
In early 1999, the source code of Heretic was published by Raven Software. This resulted in ports to Linux and other operating systems, and updates to the Heretic engine to utilize 3D acceleration.
players: single player, multiplayer (LAN / local, co-op, Modem)
input: keyboard, mouse, joystick
distribution: 3,5 floppy disk, cd-rom
sound: Adlib, Sound Blaster
Abandonware DOS popularity: low