You don't need to comply with all the licenses at once. Assets listed under multiple licenses like that can be reused under any one of those licenses, at your choice. That said, requirements differ: for CC-BY you only need to name the author, and if possible have a link back to where you got the assets (in the absence of more specific attribution instructions, that seems to be the common practice). For CC-BY-SA, you also have to make it clear that your version of the assets is distributed under the same license. A one-liner to that effect should do it in a pinch. For the GPL it's more complicated, ideally you should include a copy with your game, or at least a standard notice as explained here: http://www.gnu.org/licenses/gpl-howto.html. But I think that can be just a file included in the package, not necessarily presented to the user in-game.

Essentially, show good faith and nobody's going to fuss about the details. If in doubt, ask the author, but the whole point of open licenses is that you shouldn't need to.

Something to note, with any of the licenses (except CC0), you do need to include a copy of the full text of the license with your project.  You don't need to make the player read any of it, but you do need to make sure it is available if they are interested.

To make sure everything is spelled out nice and clearly for my projects, I include a README.TXT file which lists the stuff used under various licenses like this:

This software uses the SDL and SdlDotNet libraries under terms of the GNU LGPL license, see Readme-SDL.txt and LGPL-License.txt for details.

This software uses the OpenTK library under terms of the OpenTK license, see OpenTK-License.txt for details.

I guess you would have a line like:

This software uses the artwork '16x16 Snowy Town Tiles' by Sharm, available at http://opengameart.org/content/16x16-snowy-town-tiles and used under terms of the CC-BY-3.0 license, see CC-BY-3.0.txt for details.

Of course, it's polite to also include a mention in any in-game 'Credits' listing you may have.

If you're on a closed distribution format (IOS, PSN, etc) where the player can't just go browse around for your README.TXT file, you may want to a 'Legal' or 'Copyright Information' screen that mirrors the above lanuage and then lists the full text of the license.

Finally, since you mention reading the FAQ and still having questions, I've recently undertaken and effort to revise the license section of the site faq, if you've got a moment, I'd love to hear any feedback you have for it:

http://opengameart.org/forumtopic/site-faqsubmission-guidelines-updatesc...

Wow, I'll be darned. I didn't think you had to include a copy of the license text for CC-BY-(SA). It is not clearly stated in the human-readable version. But your comment made me look up the full text, and sure enough, right in section 4-a:

You must include a copy of, or the Uniform Resource Identifier for, this License with every copy or phonorecord of the Work You distribute

Maybe this should also be noted in the updated FAQ (if that will ever actually go live).

Derivative versions of the files may or may not fall under the same license as the original depending on which license you choose to follow. Remember, you only need one of them. And then there's this bit:

You must include a copy of, or the Uniform Resource Identifier for, this License

(emphasis mine) -- you don't actually have to include the whole, lawyer-readable text of a Creative Commons license if that's inconvenient, just a link to it. Much like the CC license selector does for you.

I think if you edit the originals without referencing Sharm's, such that the end result is sufficiently unique it would only count as a derivative of Surt's original, which is CC0.

And like claudeb says, you don't have to follow ALL licenses. You may pick one.

I haven't been able to determine what Creative Commons means by Uniform Resource Identifier, but it may be that a link satisfies it. Whatever it is, CC says you may include it, instead of the full license text.

@claudeb:

Yeah, that's a good spot, I was going off of the 'appropriate credit' pop up summary which just says:

'If supplied, you must provide the name of the creator and attribution parties, a copyright notice, a license notice, a disclaimer notice, and a link to the material.'

But the full text is pretty clear that just a link will l do.

On that note, I'll go update my update to the FAQ/guidelines to make this point very clear.

It's also worth noting that some licenses do require you to distribute the actual license text.

@DezrasDragons:

According to Wikipedia, a web address (URL) counts as a URI:

https://en.wikipedia.org/wiki/Uniform_Resource_Identifier

So just a web link like:

http://creativecommons.org/licenses/by/3.0/

or

http://creativecommons.org/licenses/by/3.0/legalcode.txt

should be fine.

@xhunterko:

You are right to be mindful of your package size on mobile platforms, but just for refrence the complete uncompressed text of the CC-BY 3.0 license takes up 20kb of space so it isn't likely to put you over budget.

Since mobiles don't always let users browse around the files in package a URL link in your credits or legal screen should be fine, and (hopefully) much easier to do than trying to replicate the work yourself.

One more thing to note, since you mention distributing CC-BY stuff on a mobile platform, be aware, all the CC licenses above CC0 contain a provision against applying 'legal terms or technological measures that legally restrict others from doing anything the license permits.'  Translation: No DRM.

In this case, pretty Sharm is on record waiving the DRM restriction for all her OGA posts, but you might contact her directly and ask for an exception or that she consider adding OGA-BY-3.0 to the licenses for this work.  That license was added more recently and is pretty much 'CC-BY-3.0 sans the anti-DRM lingo'.

whoops, see you were talking about flash distribution not mobile.

Not sure how the DRM stuff applies to flash distributions, but like I say for this particular piece, contact Sharm and you should be fine.

I'd say that's the consensus.

Rather - that is the consensus on CC-BY or CC-BY-SA. The tileset may alternatively be used under the terms of GPL 2.0 or GPL 3.0. These licenses require that you include a copy of the license text (to the best of my knowledge).

I can't think of a good reason why you would choose one of those licenses though.

Yes, something to the effect of:

This game uses art from the work '16x16 Snowy Town Tiles' by Sharm, available at: http://opengameart.org/content/16x16-snowy-town-tiles and used under terms of the CC-BY-3.0 license, see http://creativecommons.org/licenses/by/3.0 for the complete license terms and details.

Should be fine.  You may also want to toss a post up on the submission page just to let Sharm know you found the work useful.  Not strictly required but I'll be she'd be glad to hear it. :)

"Since mobiles don't always let users browse around the files in package a URL link in your credits or legal screen should be fine, and (hopefully) much easier to do than trying to replicate the work yourself."

This is one of the things I've wondered about. I stick the gpl.txt if required into my archive, but is this sufficient for a device where even though it's in the package, lack of root privileges means the users can't view that...?

I also typically put a link in my apps to a help page which includes the CC URLs and a link to the GPL (but not the full text), but in some cases this is an online web page - I have wondered if this is fine for CC licences at least (the help page is typically included in the archive too, but again, the user generally can't access that on a non-rooted mobile device).

> This is one of the things I've wondered about. I stick the gpl.txt if required into my archive, but is this sufficient for a device where even though it's in the package, lack of root privileges means the users can't view that...?

Yeah, I've wondered the same thing myself.  It seems to fit the letter of the license.   In fact, even if it was not sufficient, I would probably want to include the gpl.txt in the package anyway, since the license clearly reads that you must include it.   But at the same time, it does seem to miss the spirit of the thing.  The GPL faq actually gives pretty clear voice to their intent that end users be able to read the license:

http://www.gnu.org/licenses/gpl-faq.html#WhyMustIInclude

But then making sure users can read the full version of the text from within your app, I don't know, seems a bit redundant.  I guess you could just have it appear in full at the end of your credits or legal screens....

> I also typically put a link in my apps to a help page which includes the CC URLs and a link to the GPL (but not the full text), but in some cases this is an online web page - I have wondered if this is fine for CC licences at least (the help page is typically included in the archive too, but again, the user generally can't access that on a non-rooted mobile device).

As long as the URL is readable, I think that's ok.  I mean I don't thing it matters if the user can't directly click on it and be taken to the web site, if that's what you're asking.

Based on the above discussion in this post, it seems just a link the CC web page for the license is explicitly enough for the CC licenses.  But based on the above link to the GPL faq, it is explicitly not enough for the GPL.