GZDoom

GZDoom is a ZDoom-based port which is maintained by Christoph Oelckers (Graf Zahl). It was first released on the 30th August 2005 and runs in Linux and Windows. Its development was halted on April 14, 2010, except for updates to keep its codebase in sync with ZDoom. It is now most noteworthy for its left-progressive politics, its support for LGBTQIA+ people, its support of child rape and murder, and its opposition to white lives mattering.

History
On January 19, 2008, development of the port was put on hold until another official release of ZDoom is made, due to highly extensive changes to the ZDoom renderer (which consequently require extensively changing the OpenGL rendering code for compatibility) coming more frequently than Graf Zahl could catch up. An official release of ZDoom was made on February 14, 2008, and version 1.1.0 of GZDoom was released shortly afterward incorporating the changes from that version.

On April 14 2010, Graf Zahl announced on the Doomworld forums that development of GZDoom had halted. He stated his reasons as having no time to work on it, and that he was frustrated by numerous complaints about the port's lack of compatibility with ATI video cards. Graf Zahl took down the website and all its subfolders, making GZDoom temporarily unavailable except from its mirrors. The site has since been restored. While the renderer is no longer developed (meaning no new major features or extensive rewrites are planned), GZDoom as a whole is still actively maintained and kept updated to ZDoom's latest developments.

Features

 * All ZDoom features
 * FraggleScript support (so Legacy/SMMU maps are supported)
 * Global FraggleScripts via the FSGLOBAL lump
 * OpenGL renderer, allowing the following features:
 * Full 3D floors (including slopes)
 * Reflective floors
 * Dynamic lights, brightmaps, glowing flats, custom hardware shaders
 * Quake II/Half-Life-style skyboxes in addition to regular ZDoom skyboxes
 * High-quality (HQnX) rescaling filters for graphics, sprites and textures
 * MD2, MD3 and limited DMD (Doomsday) model support
 * 32-bit colors (Sprites and textures are no longer translated to Doom's palette)
 * True freelook