Ok, I'm not a team member but I had a looky and noticed that the thread was closed - which is a shame because some further clarification might be needed. I havn't read the terms and conditions yet, but as far as I know Doom 3 and Id's Doom3 SDK are not released under the GPL. Id only release their code as open source (quite a different thing from letting people play with the source code) several years after release and the shelf life of the product has expired. Neither is GPL a 'non commercial' or 'free' license, it just happens that a lot of free software uses GPL. Meeting the (fairly hefty) requirements of the GPL will almost certainly infringe Id's own copyright as you will be granting the right for anyone to distribute the code commercially (doh). And, just in case you havn't got the gist of this post yet, the GPL has been designed exclusively for the distrubtion of software code. It is next to useless for licensing creative content such as audio, textures, level designs and so on. The deeds offered by Creative Commons are much better suited for that kind of thing. In short. GPL is wholesome and good, but unless you specifically know otherwise, steer well clear. Id will probably mention terms and conditions for distributing Mods in one of their readme files.
