own). Although each particular level is credited to one runner, the ideas and techniques used are iterative and collaborative in nature, with each runner picking up tips and ideas from the others, so that speeds keep improving beyond what was thought possible as the runs are further optimized and new tricks or routes are discovered. Further time improvements of the continuous whole game run were achieved into the 21st century. In addition, many thousands of individual level runs are kept at Speed Demos Archive's Quake section, including many on custom maps. Speedrunning is a counterpart to multiplayer modes in making Quake one of the first games promoted as a virtual sport. Legacy The source code of the Quake and QuakeWorld engines was licensed under the GNU GPL-2.0-or-later on December 21, 1999. The id Software maps, objects, textures, sounds, and other creative works remain under their original proprietary license. The shareware distribution of Quake is still freely redistributable and usable with the GPLed engine code. One must purchase a copy of Quake in order to receive the registered version of the game which includes more single-player episodes and the deathmatch maps. Based on the success of the first Quake game, and later published Quake II and Quake III Arena, Quake 4 was released in October 2005, developed by Raven Software using the Doom 3 engine. Quake was the game primarily responsible for the emergence of the machinima artform of films made in game engines, thanks to edited Quake demos such as Ranger Gone Bad and Blahbalicious, the in-game film The Devil's Covenant, and the in-game-rendered, four-hour epic film The Seal of Nehahra. On June 22, 2006, it had been ten years since the original uploading of the game to cdrom.com archives. Many Internet forums had topics about it, and it was a front-page story on Slashdot. On October 11, 2006, John Romero released the original map files for all of the levels in Quake . Quake has four sequels: Quake II, Quake III Arena, Quake 4, and Enemy Territory: Quake Wars. In 2002, a version of Quake was produced for mobile phones. A copy of Quake was also released as a compilation in 2001, labeled Ultimate Quake, which included the original Quake, Quake II, and Quake III Arena which was published by Activision. In 2008, Quake was honored at the 59th Annual Technology & Engineering Emmy Awards for advancing the art