CodeRED: Alien Arena

Alien Arena is a free, stand-alone first-person shooter computer game based on source code released by id Software. Begun by COR Entertainment in 2004, the game combines a 1950s-era sci-fi atmosphere with gameplay similar to the Quake, Doom, and Unreal Tournament series. Alien Arena focuses mainly on online multiplayer action, although it does contain single-player matches against bots.

Alien Arena has been released for Microsoft Windows, Linux and FreeBSD. The game has been free to play since its inception, and there are currently no plans to change it to a pay-to-play format. However, as of version 7.20, it features in-game advertising, in the main menu and in some maps. While the game's content is proprietary, the CRX engine is open source.

Gameplay
The game features an internal server browser for finding other players online, and the external Galaxy program performs the same function without having to launch the game, akin to The All-Seeing Eye. It also serves as an IRC client for chat between players. The game uses modified Quake II physics. Most Quake II trickjumps, such as strafejumping, will work in Alien Arena. However, dodging, which isn't found in Quake II, has also been added to the game.

Game engine
The game is powered by the id Tech 2-based CRX game engine, which has been rewritten to include support for such features as 32-bit high-resolution textures, 3D models used as architecture in maps, GLSL per-pixel lighting effects, parallax mapping, normal mapping, server-side antilag code, shaders (GLSL and rscript), textured particles, semi-true reflective water with per-pixel distortion shaders, reflective surfaces on entities, light bloom, real-time shadows, overbright bits, real-time vertex lighting, and other graphical effects, all of which can be turned on or off in the menu. As of CRX version 7.30, OpenAL is used for sound on all platforms.

History
As of July 18, 2010, the latest version of the game is version 7.45. Although it had been in development since 2003, Alien Arena was first released as a beta in August 2004, with the title CodeRED: Alien Arena. Two single-player, campaign-style games, CodeRED: Battle for Earth and CodeRED: Martian Chronicles, were released during 2003. Following these games, Alien Arena received greater development focus. The final upgrade to the two single-player games was made available on February 18, 2005. The "CodeRED" title continued to be used until Alien Arena 2006 was released in November 2005, promoted as a "sequel" to the old CodeRED version. Alien Arena 2007 (CRX version 6.00) was released in September 2006, and Alien Arena 2008 (CRX version 7.00) appeared in March 2008. Alien Arena 2009 (CRX version 7.30) was released in June 2009. Alien Arena 2010 (CRX version 7.45) was released on July 29, 2010.

Critical Reception
Alien Arena has been compared to Quake III and Unreal Tournament, and is considered one of the best free first-person shooters. GameSpot noted the use of '60s-style sci-fi imagery and good selection of weapons and maps.

Competitive Tournaments
The Alien Arena community holds various periodical tournaments in which players can compete. These range from Cups and Ladders to weekly free-for-all matches.