id Software is to release the source code for its 2004 shooter Doom 3 to the public later this year, technical director John Carmack has announced.

Speaking during his keynote at this year's QuakeCon event in Dallas, Carmack revealed that parent company ZeniMax had given it permission to do so, and that the code will be available some time after the release of Rage in October.

He added that it needed a quick polish before you can all get your hands on it, and that it still has to be run past legal.

He then called on other developers to follow suit and release some of their old code, arguing that it helps young developers better learn their trade.