The license situation with this game is interesting. Carmack based this new port on an updated "Redux" version of his original codebase which is under GPL, so the resulting iPhone game is under GPL as well. But the iPhone user cannot benefit from the free license: although the source is available, it's not possible to install a freshly compiled version of the game on the device.

I suppose that someone could submit a free version of the app to the App Store, but Apple would probably reject it as a duplicate. (I'm not sure if Wolf3D includes artwork or other external assets that are not GPL'd. If so, then a free version would have to provide replacements for those assets, which would essentially make it a different game.)

Here's a question which I would love to have answered: does the "anti-tivoization clause" in version 3 of the GPL prevent the distribution of a GPLv3 application on an iPhone-style closed platform? Or is "tivoization" strictly limited to code that's shipped with hardware?