Engine bugs in Heretic

From DoomWiki.org

A Heretic engine bug is a limitation or an oddity present in Raven Software's modification of the Doom engine for Heretic. For errors in map design, even those related to a specific item below, see the article about that map.

Note that playing with a source port may, while removing some or even the majority of the bugs listed below, introduce other bugs which are not listed here (although details may be present in the article about the source port in question).


This table classifies anomalies in a very broad way; see the individual articles for details.

  • Cause — The general category of underlying problem:
    • Most bugs are due to algorithms which fail to account for all possible inputs, apply conditional statements in an illogical sequence, or have unforeseen consequences in particular game situations.
      • A few of these arise from simple typos in the source code.
    • Improperly constructed linedefs, with orphaned tags or incorrectly placed textures, can also induce various strange behaviors.
    • The Doom engine includes few safeguards against overflow conditions.
    • Line-of-sight calculations, rendering algorithms, and the BSP tree are also susceptible to roundoff errors.
    • The engine imposes a number of static limits on Thing placement and map construction, which sometimes fix one problem by creating another.
  • Fatal bugs are those where the engine crashes (often with the Venetian blind effect) or else exits the game in a controlled fashion, usually with an error message. Y* means that termination is possible, but not inevitable. N* means that the program keeps running, but that rendering or character behavior may be sufficiently compromised that meaningful gameplay becomes impossible.
  • A bug is inherited if it is a direct consequence or extension of a bug which occurred in the Doom v1.2 codebase upon which Heretic was built.
  • Fixed in 1.3 — Some bugs appear only in versions of Heretic prior to v1.3.
  • A bug has a workaround if it can be avoided by reasonable compromises in map design, such as when matching every linedef tag to at least one sector, but not when removing invulnerabilities from every level containing a sky texture, or also by convenient precautions and other measures taken by the program user, such as when increasing the mouse sensitivity through the configuration file directly, instead of using the menu. S means that the bug can be avoided only by making one's map smaller or less complex.
  • A bug is a loophole if it can be abused to the player's advantage (especially during speedruns or deathmatches).
Phenomenon Cause Fatal? Inherited? Fixed in
Workaround? Loophole?
-timedemo parameter desyncs in Heretic and Hexen N N N N N
Firemace randomization bugs N N Y N N
Tomed firemace instant-kills iron liches N N Y N Y
Incorrect terrain effects when straddling sector boundaries N N N N N
Incorrect artifact displayed when loading a saved game N N N N N
Invalid map number in recorded demo Algorithm N* N N N N
Invulnerability colormap bug Algorithm N Y N N N
Heretic powerup visual effects conflict N N N N N
Heretic and Hexen sky seam bug N N N N N
Falling gargoyle can explode multiple times N N N N N
Falling gargoyle can fail to explode N N N N N
Flying enemies stick to other monsters and players Algorithm N N N N N
Monsters can see through walls Algorithm N Y N Y N
Landing on solid objects causes erroneous air control and friction Algorithm N N N N Y
Vertical cutoff of partially invisible sprites Static limit N Y N N N
Barrel suicide (with exploding pods) Algorithm N Y N N Y
Choppy player movement when suffering lava damage Algorithm N N N N N
Voodoo doll skull pop teleportation Algorithm N Y N N N
Automap scale preserved after warps in Heretic and Hexen
Heretic ambient sounds stop playing N N N S N
Wings of Wrath can be carried between levels N N N N Y

See also[edit]