It is awesome to see the Doom 3 id Tech 4 Game Engine source code released and available at https://github.com/TTimo/doomhttp://www.blogger.com/img/blank.gif3.gpl. This does not include the Doom 3 assets, but is awesome to see all the code on GitHub.
Looking at the source code, a few similarities show up with other engines.
Curl for HTTP requests (common in a few engines).
OpenAL for audio (nice to see, also fairly common).
Ogg Vorbis format for sounds (used in a few places).
DirectX SDK requirement (for Windows).
JPEG (version 6) for images.
Some other notes at a glance:
Custom UI code.
Tools for dialogs, material editors, particles and more.
It is awesome to see this, and many thanks to John Carmack and the id Tech team for sharing. I will definitely be looking at this further and will be anxious to see what the gaming community mods and comes up with, using this code.
I will be certain to be reading more of the code which looks in general to be of quite a high quality. There are not a lot of comments (which would be nice to have) but overall the functions and classes are clearely named and look to be a pleasure to read. Also, in a number of the external libraries are the custom documentaion, like Curl, OpenAL etc. so that is nice to see how those APIs are being used, and what else can be extended.
Lots of fun, I have been busy recently, but will certainly have to devote some time to this.