Raven Software teamed up with id Software for the second time in its creation of the hit fantasy action game Heretic, which was released on December 23rd 1994. Based on a modified Doom engine, Heretic pioneered a revolutionary new inventory system for character item use that has become commonplace in the FPS genre. id Software published the game under its flag and it was distributed by GT Interactive.
Players took the role of a nameless Elven hero (given the name Corvus in Heretic II) whose race, the Sidhe, was nearly eliminated by a horde of evil monsters from another dimension. The first episode of Heretic was released as shareware as a precursor to the full version of the game.
Heretic won several awards for excellence, appeared in such notable publications as USA Today and Playboy, and opened many new doors in the computer gaming software industry for Raven Software and its team of developers. Heretic was Raven Software's most popular, highest acclaimed, biggest selling game to that point.
After its big success, two additional episodes were released for free, upgrading the normal Heretic to Heretic: Shadow of the Serpent Riders (v1.3). The original version of Heretic with three episodes was subsequently discontinued.
Some of the modifications Raven made to the Doom engine for Heretic were flight, sectors that can push the player, an inventory system, ambient sounds, translucency, looking up and down and pushable objects.
The world of Parthoris was populated by many people who divided themselves into seven great nations, as well as the mystic Sidhe elves. It was these elves who kept the Tomes of Power and the sacred candle flames which eternally burned to represent the armies of the world.
The Sidhe believed in a prophecy of Armageddon, and their prophecy ultimately proved itself true when from the east came the three terrible Serpent Riders cloaked in black. They were great sorcerers, and they demonstrated their power by quelling the wars of the eastern provinces. Soon the men of the seven nations turned to their worship and built a great temple in their honor. Upon the temple was the Sign, a crossed trident, and the worshippers came to call themselves the Order of the Sign. The deeper into reverence of the Riders' dark ways they fell, the more they were sapped of their free will and spirit. Once all of the seven realms were theirs, the two eldest Riders departed, leaving D'Sparil alone to prepare the world for destruction.
Recognizing the fulfillment of prophecy, the Sidhe refused to follow in the worship of D'Sparil and thus they were set apart from the other people of the world. Once sacred guardians, they were now heretics, hunted and hated everywhere they went. D'Sparil's disciples turned the minds of the seven kings toward conquest of the Sidhe realm, and when the Seven Armies marched upon them, the Sidhe Elders extinguished the sacred flames, destroying them all.
D'Sparil was enraged and in the chamber of the Elders he stirred up a storm of white-hot flame, killing them all. The earth burst open beneath their charred bodies and from within poured legions of the undead as well as murderous beasts from worlds beyond. This new army overwhelmed the Sidhe and slaughtered them in untold numbers. In only one day, their civilization was destroyed and their survivors were scattered far and wide. The darkling creatures had carried off the Tomes of Power and the other artifacts of the Sidhe as spoils of war. Left defenseless, it was surely only a matter of time before all Sidhe perished under the Order of the Triad's unyielding fury.
Most of the few remaining Sidhe hid themselves away, but Corvus was determined to have revenge. Heading east into the wilderness he came upon the City of the Damned, where the very air reeked with rot and decay and the only sounds were the screams of foul creatures seeking his blood. Armed only with his staff and Elven Wand, he had little hope to survive. So began the downfall of D'Sparil and the salvation of Parthoris.
 Heretic skill levels
1. Thou needeth a wet-nurse: Damage taken is halved; number of monsters is decreased; number of powerups and items is increased; ammo powerups give 50% more than normal. The game automatically uses quartz flasks and mystic urns to prevent the player from dying.
2. Yellowbellies-r-us: Number of monsters is decreased; number of powerups and items is increased. Otherwise similar to skill 3.
3. Bringest them oneth: This is the normal skill level.
4. Thou art a smite-meister: Similar to skill 3, but the number of monsters is greater; the number of items and powerups is decreased.
5. Black plague possesses thee: Similar to skill 4, but ammo powerups give 50% more than normal; monsters attack and move 300% faster; enemy missiles fly 300% faster; cheating is disabled.
The skill names parody the often badly understood Early Modern English common throughout the fantasy genre. 1, 3 and 5 are grammatically non-standard; they should be Thou needest a wet-nurse, Bring them on, and Black plague possesseth thee; the mix of English and German in 4's smite-meister is unusual, and 2 makes an out-of-place anachronistic reference to Toys-R-Us.
 Enemies, weapons, items
1Can only be found in the full version of the game.
2These items make a reappearance in Hexen.
 Heretic levels
City of the Damned (Episode 1) (The only one in shareware) Sky Color: Grey
- E1M1: The Docks
- E1M2: The Dungeons
- E1M3: The Gatehouse
- E1M4: The Guard Tower
- E1M5: The Citadel
- E1M6: The Cathedral (secret exit)
- E1M7: The Crypts
- E1M8: Hell's Maw (Iron Liches are bosses)
- E1M9: The Graveyard (secret level)
Hell's Maw (Episode 2) Sky Color: Red
- E2M1: The Crater
- E2M2: The Lava Pits
- E2M3: The River of Fire
- E2M4: The Ice Grotto (secret exit)
- E2M5: The Catacombs
- E2M6: The Labyrinth
- E2M7: The Great Hall
- E2M8: The Portals of Chaos (Maulotaurs are bosses)
- E2M9: The Glacier (secret level)
The Dome of D'Sparil (Episode 3) Sky Color: Blue
- E3M1: The Storehouse
- E3M2: The Cesspool
- E3M3: The Confluence
- E3M4: The Azure Fortress (secret exit)
- E3M5: The Ophidian Lair
- E3M6: The Halls of Fear
- E3M7: The Chasm
- E3M8: D'Sparil's Keep (D'Sparil is boss)
- E3M9: The Aquifer (secret level)
The Ossuary (Episode 4) (Heretic: Shadow of the Serpent Riders only) Sky Color: Grey
- E4M1: Catafalque
- E4M2: Blockhouse
- E4M3: Ambulatory
- E4M4: Sepulcher (secret exit)
- E4M5: Great Stair
- E4M6: Halls of the Apostate
- E4M7: Ramparts of Perdition
- E4M8: Shattered Bridge (Iron Liches are bosses)
- E4M9: Mausoleum (secret level)
The Stagnant Demesne (Episode 5) (Heretic: Shadow of the Serpent Riders only) Sky Color: Blue
- E5M1: Ochre Cliffs
- E5M2: Rapids
- E5M3: Quay (secret exit)
- E5M4: Courtyard
- E5M5: Hydratyr
- E5M6: Colonnade
- E5M7: Foetid Manse
- E5M8: Field of Judgement (Maulotaurs are bosses)
- E5M9: Skein of D'Sparil (secret level)
Fate's Path (Episode 6) Sky Color: Grey
These three levels, seemingly built for Deathmatch are untitled in the game itself and can only be accessed via the "engage##" cheat or the command line (they don't appear on the episode select screen). The first two names resulted from suggestions by designer Michael Raymond-Judy in an interview; whilst the name of the third map and the "episode name" were unofficially made up by fans and are widely accepted among the community.
Note that E6M3 appears as E4M1 in the original registered version of Heretic, hidden in the same way as the above details for Shadow of the Serpent Riders.
 Source code release
- Main article: Raven source code licensing
On January 11, 1999, the source code for both Heretic and Hexen was released by Raven Software under a restrictive EULA  which prohibited many uses of the code, and was incompatible with the GNU GPL. This rendered it impossible to create a properly open source source port (under the Open Source Definition) for either game. On September 4, 2008, the source code for both games was rereleased under the GPL .
Heretic, like Doom, has a demo rotation; however, two of them go out of sync in Shadow of the Serpent Riders. The first demo makes it to the crossbow and begins shooting at a torch before being slashed to death by Sabreclaws. The third demo goes out of sync almost immediately, the player starts running into walls, shooting at the ceiling and never leaves the starting room.
 See also
- Official Heretic website
- The Heretic FAQ
- Category at ODP
- Heretic at MobyGames
|Official source ports|
|Based on||Name||Base for|
|Source code genealogy|
|Based on||Name||Base for|
|Doom v1.2||Heretic||BeOS Heretic|