[No [but]] Mixing GPL and nonfree assets in a project

[Matt]

(in particular: including modified Freedoom assets and modified Doom assets in a single mod download)

I assume just putting them all together and distributing as a single undifferentiated thing would be a big no-no under the GPL.

Is it acceptable to hive off the GPL assets and say those are subject to the GPL and everything else is subject to another licence?

EDIT: Guess not.

However, in many cases you can distribute the GPL-covered software alongside your proprietary system. To do this validly, you must make sure that the free and nonfree programs communicate at arms length, that they are not combined in a way that would make them effectively a single program.

[Graf Zahl]

Freedoom is not GPL, though.

[Gez]

And this kind of prohibition is exactly why it's not GPL, too.

[Matt]

Thanks for the correction! Reading up on the BSD now...