ZDoom

ZDoom is a discontinued source port that was popular for many years because of its rich feature-set. It had Boom compatibility; complete support for Heretic, Hexen, Strife, and Chex Quest; as well as many additional new features, including slopes, uncapped framerate, and z-clipping. It was originally based on a merger of the ATB Doom and NTDOOM source ports.

The large number of editing features supported by ZDoom made it the port of choice for several independent game projects, notably Foreverhood, Action Doom 2: Urban Brawl, Chex Quest 3, and Harmony. ZDoom also served as a popular code base to build upon, with numerous other source ports derived from it or using portions of its code.

ZDoom was created by Marisa Heit (Randi) soon after the Doom engine source code was released in 1997, and by 1999 many foundational features had been added. Others also made signficiant contributions over the years, including Christoph Oelckers (Graf Zahl) and Braden Obrzut (Blzut3).

Although Heit officially ceased the project in January 2017, the ZDoom legacy continues to thrive in several forks, notably GZDoom and Zandronum.

Features

 * New gameplay options, including crosshairs, free look, jumping, swimming, and crouching.
 * Options for the HUD, including an alternative layout.
 * A console that allows the user to enter commands and edit variables.
 * High screen resolutions, including widescreen, with optimizations for modern processors.
 * Implementation of Heretic, Hexen, and Strife's editing features, including ACS, hubs, terrain effects, the Hexen map format, and more.
 * A large array of extensions to ACS, including new operations, functions, and a more advanced bytecode format.
 * Created the DECORATE content definition language for actors, states, weapons, inventory, and more.
 * Support for all Doom engine games.
 * Removal of most vanilla Doom static limits.
 * Improvements to vanilla Doom's flawed collision detection.
 * Support for almost all of Boom's editing features.
 * Support for several MBF extensions, including friendly monsters and loading DeHackEd patches from within WAD files.
 * Support for UDMF.
 * Translucency in regular, additive, subtractive, and reverse subtractive varieties.
 * Choice of multiple MIDI devices, including OPL emulation, Gravis Ultrasound emulation, TiMidity++ and FluidSynth among others.
 * Many supported sound and image formats (see for a complete listing).
 * Enhanced texture definition lump allowing use of any graphics used by the game as patches, and allowing effects such as scaling, blending, rotating, and mirroring.
 * Flat and texture mixing.
 * UDP Internet and LAN networking inherited from Linux Doom.
 * Walking over/under monsters and other things.
 * Runs under Windows 98, NT, XP, Linux and Mac OS X.
 * Support for Doom Connector and Player Connector network games.
 * Portals, 3D floors, 3D middle textures, slopes and colored lighting.
 * Decals on walls for scorch marks and blood splatter.
 * Support for FraggleScript with permission of Simon Howard (Fraggle).
 * Support for custom player skins compatible with Doom Legacy.
 * A chasecam and many camera effects, including Duke Nukem-style security camera and Unreal-style skyboxes. Cameras can replace the player view, allowing for scripted cutscenes or alternative gameplay, such as mimicking a sidescroller.
 * Support for using the features of every Doom engine game in all of them &mdash; for example, a Doom map can feature Strife conversations, Hexen scripting and actors that use Heretic codepointers.
 * Support for loading resources directly from ZIP (.pk3) or 7z (.pk7) files, making the use of the traditional WAD file format optional except for map lumps.
 * ENDOOM and animated start up screen support
 * Quality using the popular  library, but in a restricted manner to conserve memory

Classic Doom-engine IWADs

 * Doom v1.2 or later, including Ultimate Doom
 * Doom II; development versions even support the modified IWAD included as a bonus with Doom 3: BFG Edition
 * Final Doom
 * Heretic
 * Hexen
 * Strife, including both demo versions
 * Chex Quest

Stand-alone mods
In addition, ZDoom offers aliases that allow use of free IWAD projects Freedoom and Blasphemer as alternatives instead of replacements. See for further information.
 * Action Doom II: Urban Brawl
 * The Adventures of Square
 * Chex Quest 3
 * Hacx v1.2 or v2.0
 * Harmony
 * Hedon
 * Rise of the Wool Ball

Ports based on recent versions of ZDoom
These ports support most or all of the features listed above.
 * GZDoom, ZDoom's successor
 * Zandronum and its predecessor, Skulltag
 * QZDoom, Experimental port

Ports based on older versions of ZDoom
These ports are not necessarily compatible with recent ZDoom mods.
 * bZdoom
 * csDoom
 * Odamex
 * ManDoom
 * ZDaemon
 * ZDaemonGL
 * ZDoom Community Build
 * ZDoomGL (v1)
 * ZDoomGL (v2)