the Doom engine used in Hexen: Beyond Heretic, as well as several other new features. It also supports other games that share the Doom engine. Unlike many other source ports, ZDoom cannot play demos recorded with Vanilla Doom, including the intro demos found in the IWAD. The last version of ZDoom, was released in February 2016, and was officially discontinued on January 7, 2017. In the announcement, ZDoom's creator, Randi Heit, recommended using QZDoom or GZDoom instead. GZDoom GZDoom is a source port based on ZDoom that extends its feature set to include an OpenGL 3 renderer. It was released on August 30, 2005. GZDoom also boasts 3D floor support compatible with Doom Legacy and Vavoom, 3D model support, 360 degree skyboxes, and other features. Version 2.4.0 was the first version to be officially released on ZDoom.org alongside the release of QZDoom 1.3.0 on March 19, 2017. Skulltag and Zandronum Skulltag was one of the multiplayer-centric Doom ports based on (G)ZDoom. It added 32-player multiplayer and different game modes: standard types such as deathmatch and capture the flag, and other modes such as co-operative waves and invasion maps. Skulltag had support for 3D models and high-resolution textures. Skulltag received a final update on November 7, 2010, and was shut down on June 7, 2012. Skulltag 98e was succeeded by Zandronum, which is made by the same developers after the original creator moved to another project. Zandronum was first released as version 1.0 on August 24, 2012. Zandronum improved support up to 64 players online per server and introduced Last Man Standing and other, more original game modes. ZDaemon ZDaemon is an online multiplayer source port for Doom. It is a fork of another source port, Client/Server Doom or csDoom, the first stable source port to allow playing on the Internet by using client/server network code (from QuakeWorld). With ZDaemon, players create an account and can then easily connect to multiplayer servers with the included server browser (ZDaemon Launcher). The ZDaemon Launcher also features access to the ZDaemon IRC channel through their own client called "ZRC" (ZDaemon Relay Chat). To cut down on impersonation and spoofing, version 1.09 introduced in-game nick authentication, which allows players to use aliases (such as for clan tags), but only when they actually own the nick. ZDaemon also collects statistics from servers that have it enabled, as well as experience points, allowing players to level up