itch.io

Unfortunately, the maintainers of all three major definitions of libre stuff (the Open Source Definition, the Debian Free Software Guidelines, and the Free Software Foundation’s Four Software Freedoms) have decided that “don’t resell as-is” disqualifies a license.

(I see that requirement on tons of assets here, and I just immediately close the tab.)

…and separating “as part of a game” from “as part of a compilation of assets” is a legal mess, so Creative Commons only offers that via the NonCommercial option, which people avoid because even that is a legal nightmare. (Can I be sued because I posted a CC BY-NC image on a blog with Google AdSense ads? Nobody knows for sure. The boundary between commercial and non-commercial use is decided by going to court over it.)

If you really want that, your only option is to specify a proprietary license… and going through the mailing lists for places like the OSI (who maintain the Open Source Definition) will give a ready sampler of why you want a proper lawyer to design a license.

The consensus behind that mindset is that:

1. Places like Africa still need the ability to do the equivalent of selling shareware/freeware floppies for a nominal fee in the 1990s (eg. selling Wikipedia DVD sets for places without reliable Internet access) and trying to legally constrain how much is acceptable to charge is a legal mess.
2. Bad actors are going to resell stuff if they think they can get away with it, regardless of your license.
3. Outside of things like DVD sets for people without Internet, good-faith actors will be driven off by the license allowing buyers to then give away copies or upload them to the Internet Archive or whatever. (And the threat that PayPal might reverse the charges as fraudulent if they don’t make it clear to the buyer that the compilation is all free stuff you could download yourself.)
4. If you need more assurance, a copyleft requirement like the ShareAlike clause in the CC BY-SA scares off abuse more strongly… and because of how copyright works, it only applies to “derivative works”, not “aggregation”.

Here’s a quick TL;DR of aggregation vs. derivative works:

1. If someone combines your art into a single-PNG tile atlas, the whole atlas would be a derivative work.
2. If someone bakes your art into a single-EXE game, the game would be a derivative work.
3. If someone puts your art into a folder or Zip file as part of their game, and it’s easy for the player to replace your art with something else and have the game function identically aside from displaying different art, then it’s aggregation and you can combine GPL code and CC BY-SA art in the same game, despite the GPL and BY-SA having incompatible copyleft requirements.