Changes

== History ==

== History ==

Doom's engine was revolutionary in its' day, being one of the first games to feature almost true 3D environments. More about the engine's capabilities and shortcomings can be read on [http://doom.wikia.com/ The Doom Wiki]. Most notably, the Doom engine reads all its' behaviour values from a pseudorandom table in the source code. This allows for demo recording and playback, so players can share their exact play routes and others can play those routes back using the actual game engine via exchange of small demo files.

Doom's engine was revolutionary in its' day, being one of the first games to feature almost true 3D environments. More about the engine's capabilities and shortcomings can be read on [http://doomwiki.org/wiki/Entryway The Doom Wiki]. Most notably, the Doom engine reads all its' behaviour values from a pseudorandom table in the source code. This allows for demo recording and playback, so players can share their exact play routes and others can play those routes back using the actual game engine via exchange of small demo files.

id Software released the Doom source code late in 1997 under a not-for-profit license then again in late 1999 under the GNU GPL. The availability of this has encouraged ongoing development of "source ports" and continued creation of fan-made mods even today. Ports like [http://zdoom.org/ ZDoom] focus on implementing extra editing features like scripting and extra weapons/monsters although this comes at the expense of compatibility with original demos. Ports like [http://prboom.sourceforge.net/ PrBoom] focus on extending the features of the game whilst maintaining demo compatibility with the originals. The [http://prboom-plus.sourceforge.net/ PrBoom-Plus] branch of this port adds several TAS features for demo recorders and watchers such as slowdown and the ability to split demos and continue recording to a new file halfway through.

id Software released the Doom source code late in 1997 under a not-for-profit license then again in late 1999 under the GNU GPL. The availability of this has encouraged ongoing development of "source ports" and continued creation of fan-made mods even today. Ports like [http://zdoom.org/ ZDoom] focus on implementing extra editing features like scripting and extra weapons/monsters although this comes at the expense of compatibility with original demos. Ports like [http://prboom.sourceforge.net/ PrBoom] focus on extending the features of the game whilst maintaining demo compatibility with the originals. The [http://prboom-plus.sourceforge.net/ PrBoom-Plus] branch of this port adds several TAS features for demo recorders and watchers such as slowdown and the ability to split demos and continue recording to a new file halfway through.

Official competition for Doom was hosted by [http://www.doom2.net/~compet-n/index.cgi Compet-N] from 1994 to 2005. Compet-N focused on the original Doom levels as well as a limited range of fan-made modifications which were seen to be of very high quality by the Doom community. Rules for Compet-N were very strict, with demos only played with the DOS executables being allowed entry into the archive.

Official competition for Doom was hosted by [http://www.doom2.net/~compet-n/index.cgi Compet-N] from 1994 to 2005. Compet-N focused on the original Doom levels as well as a limited range of fan-made modifications which were seen to be of very high quality by the Doom community. Rules for Compet-N were very strict, with demos only played with the DOS executables being allowed entry into the archive.

Compet-N established a format for sorting demos based on both the skill level selected within the game, and the aims of the demo. Some examples are focus on achieving 100% kills on the Ultra Violence difficulty (called UV Max), or a focus on completing the levels as fast as possible without attacking any monsters (called Pacifist). A complete list of categories can be found on the [http://doom.wikia.com/wiki/Speedrun Speedrun page of the Doom Wiki].

Compet-N established a format for sorting demos based on both the skill level selected within the game, and the aims of the demo. Some examples are focus on achieving 100% kills on the Ultra Violence difficulty (called UV Max), or a focus on completing the levels as fast as possible without attacking any monsters (called Pacifist). A complete list of categories can be found on the [http://doomwiki.org/wiki/Speedrun Speedrun page of the Doom Wiki].

Today, Doom speedrunning lives on at Doug "Opulent" Merrill's [http://doomedsda.us/ Doomed Speed Demos Archive]. The Doomed SDA features a much more relaxed ruleset, accepting demos recorded with modern sourceports and for any fan-made level.

Today, Doom speedrunning lives on at Doug "Opulent" Merrill's [http://doomedsda.us/ Doomed Speed Demos Archive]. The Doomed SDA features a much more relaxed ruleset, accepting demos recorded with modern sourceports and for any fan-made level.

==== Suicide exit ====

==== Suicide exit ====

Suicide Exit (also called Deathslide) is a technique where the player intentionally kills the character to exit a level. Dead actors in the Doom engine acquire momentum on death by a weapon (which will have a degree of knockback) or by a nearby explosion. The engine considers a corpse to have 0 height, so a dead player can slide their corpse under locked doors and into otherwise unreachable places which can trigger a level exit. This was discovered in 2001 by speedrunner Vincent Catalaá. More information, including techniques and demos, can be found [http://doom.wikia.com/wiki/Suicide_exit on the Doom Wiki Suicide Exit page].

Suicide Exit (also called Deathslide) is a technique where the player intentionally kills the character to exit a level. Dead actors in the Doom engine acquire momentum on death by a weapon (which will have a degree of knockback) or by a nearby explosion. The engine considers a corpse to have 0 height, so a dead player can slide their corpse under locked doors and into otherwise unreachable places which can trigger a level exit. This was discovered in 2001 by speedrunner Vincent Catalaá. More information, including techniques and demos, can be found [http://doomwiki.org/wiki/Suicide_exit on the Doom Wiki Suicide Exit page].

==== Wallrunning ====

==== Wallrunning ====

Sprites in Doom (called Things in the engine) all have square "bounding boxes" in the Doom mapping format. As such, it's also possible to run into Things and accelerate in a similar fashion. This is known as "Thingrunning".

Sprites in Doom (called Things in the engine) all have square "bounding boxes" in the Doom mapping format. As such, it's also possible to run into Things and accelerate in a similar fashion. This is known as "Thingrunning".

An amateur player can easily wallrun on most maps, an ideal setup for thingrunning can be found in the rows of barrels present on Doom II's MAP23: Barrels o Fun. More information and demos can be found on [http://doom.wikia.com/wiki/Wallrun the Doom Wiki Wallrun page].

An amateur player can easily wallrun on most maps, an ideal setup for thingrunning can be found in the rows of barrels present on Doom II's MAP23: Barrels o Fun. More information and demos can be found on [http://doomwiki.org/wiki/Wallrunning the Doom Wiki Wallrun page].

== External Links ==

== External Links ==