The source code for id Software's Doom 3 game will be released sometime this year. While we don't have a specific date, we do know that once the game Rage is released, the company will focus on releasing Doom 3's code to the public, according to VG247.
Rage is slated to be released on the Sony PlayStation 3, the Microsoft Xbox 360, and on Microsoft Windows on October 4, 2011 in North America and October 7, 2011 in Europe. As a result, we can expect the Doom 3 source code as soon as late October.
The news was first announced at QuakeCon 2009, but id Software co-founder John Carmack confirmed it again today, during QuakeCon 2011. He also challenged other developers to release old source code, saying that it helps the development community as well as the company that makes the bold decision.
Doom 3 was developed for the Windows platform by id and published by Activision on August 3, 2004. The game was later adapted for Linux, as well as ported by Aspyr Media to Mac OS X.
Doom 4 is currently in the works, also courtesy of id Software. The game will use the company's new id Tech 5 engine and is slated for simultaneous release on PS3, Xbox 360, and Windows.
When Carmack was asked about Doom 4, he responded that this was the year of Rage. While he declared he didn't "really have anything to say about it," he did note that all the Rage guys are moving over to Doom, but that the company is still "hoping to do Rage 2."