Can I mix GPL code with assets modified under different licenses?

Question

I'm currently working on an open source video game and would like to mix licenses within the core project.

I would like to:

• License all source code I write as AGPLv3.
• License all original assets I make (space ships, character models, textures, etc) as MIT.
• Use third party assets from providers such Mixamo and NASA within the core project. I will modify these third-party assets and redistribute them along with this project where allowed by their own respective licenses.
• Include explicit notices for everything that is not AGPLv3 licensed.

I can tell AGPLv3 is quite restrictive - does it allow the above combination? The dev builds will exclude almost all of these assets or have simple placeholders, but the production builds will include all assets as the full product offering (albeit free of charge), and be distributed through various platforms.

Does AGPLv3 allow this?

Answer 1

The AGPL does not allow this for what copyright law considers to be a single work. If any part of the work is licensed under the AGPL, then the AGPL requires that the entire work is distributed under the terms of the AGPL.

However, it is not a given that a game engine and the assets of the game are a single work under copyright law. If the game can function equally well with completely different assets, like the simple placeholders you intend to use for dev builds, then copyright law will likely view the game engine and the assets as different, independent, works that happen to be bundled together in your full product.

Independent works can have completely independent license terms, so what you propose seems to be fine.

One thing to look out for: If you don't write all the source code yourself, but you use third-party libraries, then you need to make sure that those libraries have a (A)GPL-compatible license. It is not a completely settled debate if using a third-party library always creates a single derived work that includes both your code and the code from the library, but the safe option is to assume it does.