I came across an asset with 3 different licenses. The GPL 3.0 license appears to just be a newer version of the GPL 2.0. Can the GPL 2.0 be disregarded if the GPL 3.0 is complied with?
Must all conditions from all 3 licenses be met? For example, the GPL 2.0 mentions printing or displaying an appropriate copyright notice, but this seems to be absent from the CC BY-SA 3.0 license.
According to Open Game Art's FAQ:
You must follow only one of the licenses. However, when you re-distribute/edit, you are encouraged to include/use all of the licenses, so the license spectrum (and thus sum of people/projects who can use the art) doesn't shrink.
The asset is offered under different license conditions. It is your choice under which of these terms you would like to license it.
Regarding your question about the GPL 2.0 and 3.0 compatibility: No, the versions 2 and 3 of the GPL are generally not compatible. However, you need to pay close attention to the wording of the copyright message. If the work is licensed under "GNU GPL Version 2.0" it is nailed down to version 2.0 for all eternity. But when it reads "GNU GPL version 2.0 or any later version", you are allowed to "upgrade" the work to GPL 3.0 (or a version 4.0 which might exist some day). Some projects trust the Free Software Foundation to still know what they are doing in the future and use the "or later version" wording, while other projects (like the Linux kernel, for example), don't want to risk giving the FSF a carte blanche to introduce a new license which can then automatically be applied to their software.
The Free Software Foundation also has a handy table regarding combining different GPL licenses. When reading that table, you might wonder if using an asset counts as use of a library or as copying code. That's a very good question. The GPL is designed for program code, not for artwork, which makes it quite hard to interprete in that context.
About the GNU Public License (GPL) version x.
It's clearly mentioned in GPLv2 and GPLv3 declarations that you must apply this version or, at your option, newer of the license.
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Source - How to use GNU licenses for your own software
So; the parts of your program using only GPLv2 submitted code could be redistributed under GPLv2 or under GPLv3, if you want. The parts using only GPLv3 under GPLv3.
And so, your program should be redistributed under GPLv3, since GPLv3 contains everything GPLv2 contains plus added content.
And since there is 3 licenses; I think you should apply the GPLv3 on your program, plus the other license, and, as long as the licenses do not interfere with each other; you probably should apply both (GPLv3 and CC).
If the license interfere with each other; you better should contact CC's admins, the GNU's admins (or the Free Software Foundation?) and Open Game Hearth admins.
I'd recommend to put all the sources and headers under GPLv3, the documentations as well. And all the arts (drawings and such) under the CC license.
