Catacomb 3D

Catacomb 3D (also known as Catacomb 3-D: A New Dimension, Catacomb 3-D: The Descent, and Catacombs 3) is a created by id Software and published by  in November 1991. The game has a dark fantasy setting, akin to Heretic and Hexen. The player takes control of the high wizard Petton Everhail, descending into the catacombs of the Towne Cemetery to defeat the evil lich Nemesis and rescue his friend Grelminar.

id Software introduced several new concepts in Catacomb 3D, such as rendering walls with texture-mapping and showing the player's hand in the 3D view. Such concepts were further improved and extended in Wolfenstein 3D and Doom.

Development
The origin of Catacomb 3D is Catacomb by John Carmack for the PC and Apple II. This was a 2D game utilizing a third-person view from above, released in 1989-1990. It was followed up with Catacomb II, which used the same game engine with new levels. The first release of Catacomb 3D was called Catacomb 3-D: A New Dimension, but it was later re-released as Catacomb 3-D: The Descent, as well as Catacombs 3 for a re-release as commercially packaged software (the earlier versions had been released by other means such as disk magazines and downloads). The game creators were John Carmack, John Romero, Jason Blochowiak (programmers), Tom Hall (creative director), Adrian Carmack (artist), and Robert Prince (musician).

Similarities with Doom engine games

 * The player's health can be restored by collecting small blue potions, which resemble the health bonus in Doom.
 * The player's health is indicated by a face which deteriorates in condition as damage is taken, and is restored with healing.
 * The player has to collect red, yellow, blue and green keys to open doors with a matching color.
 * Level 9, Access Floor, connects in a nonlinear fashion to several other levels, similar to the hub maps in Hexen.
 * Level 14 is named The Warrens, while E3M9 of Doom is named Warrens.
 * Level 19, Halls of Blood, is set in a hellish environment with demons.
 * Uses the same pseudorandom number generator as found in the Doom source code.
 * Uses fake contrast to help accentuate the angles in the level's geometry. The game does this by using texture themes with matching lighter and darker versions of textures that can be assigned to the different faces of each cell. In Doom this effect is accomplished by applying a darker light level to walls oriented parallel to the east-west axis, while a brighter light level is applied to walls parallel to the north-south axis.

Source code release
Catacomb 3D was developed by Id Software as part of an agreement with Softdisk. Consequently, the publishing rights were initially owned by Softdisk. Eventually these rights were bought by a small company called Flat Rock Software. In 2013, Flat Rock Software introduced the Catacombs Pack: a bundle of six Catacomb games that are sold electronically through GOG. In June 2014, source port developer Braden Obrzut (Blzut3) convinced the owner of Flat Rock Software to open-source the Catacomb games under the GPL2 license. This enabled the creation of source ports for Catacomb 3D.

ReflectionHLE
Support for Catacomb 3D was added to the ReflectionHLE source port in November 2014, as of version 0.9.6. ReflectionHLE was initially developed by NY00123 as a source port of Keen Dreams for Windows and Linux. The file formats used in Keen Dreams are similar to those used in the Catacomb games, which prompted NY00123 to add support for Catacomb 3D and the Catacomb Adventure series. Since 2020 also Wolfenstein 3D and Spear of Destiny are supported. ReflectionHLE is inspired by Chocolate Doom and shares the same philosophy of preserving the look, feel, and bugs of the vanilla DOS experience. It originally started with the short-lived name of "Chocolate Keen Dreams", and had been known as "Reflection Keen" for close to 7 years.

CatacombGL
Support for Catacomb 3D was added to the CatacombGL source port in January 2020, as of version 0.4.0. CatacombGL is developed by Arno Ansems as a source port of Catacomb 3D and the Catacomb adventure series for Windows. Its main feature is the use of hardware accelerated 3D rendering via OpenGL, with support for widescreen resolutions, a customizable field of view and an uncapped framerate.