the primary competitive mod for Quake III Arena since the Cyberathlete Professional League announced CPMA as its basis for competition. CPMA includes alternative gameplays, including air-control, rebalanced weapons, instant weapon switching, and additional jumping techniques. Another mod that underwent several open beta versions and was very popular in 1999-2001 was Quake 3 Fortress (Q3F). The initial version of this game was an indirect port of the Quakeworld Team Fortress mod with many clans and leagues competing in both games simultaneously. Q3F was eventually ported to another Quake 3 mod Enemy Territory Fortress which had limited success. The developers of Q3F eventually abandoned the mod but used it to create the standalone 2003 game Wolfenstein: Enemy Territory, which uses the Quake 3 engine and is still popular with approximately 9,400 active players in 2018. Fast inverse square root Fast inverse square root, sometimes referred to as Fast InvSqrt() or by the hexadecimal constant 0x5F3759DF, is an algorithm that estimates , the reciprocal (or multiplicative inverse) of the square root of a 32-bit floating-point number in IEEE 754 floating-point format. The algorithm is best known for its implementation in the source code of Quake III Arena.At the time, it was generally computationally expensive to compute the reciprocal of a floating-point number, especially on a large scale. However, the fast inverse square root bypassed this step. Around 2002, initial speculation pointed to John Carmack as the probable author of the code, but he demurred and suggested it was written by Terje Mathisen, an accomplished assembly programmer who had previously helped id Software with Quake optimization. Mathisen had written an implementation of a similar bit of code in the late 1990s, but the original authors proved to be much further back in the history of 3D computer graphics with Gary Tarolli's implementation for the SGI Indigo as a possible earliest known use. Expansion An expansion pack titled Quake III: Team Arena was released on December 18, 2000, in North America, January 15, 2001, in Japan and January 26, in Europe. It was developed by id Software and published by Activision. The expansion focused on team-based gameplay through new game modes, as well as the addition of three new weapons (the Chaingun, Nailgun, and Prox Launcher), and new items and player models. Quake III: Team Arena was criticized, as its additions were long overdue and had already been implemented by fan modifications. Quake III: Gold