You can use it comercially long as you follow the liscense.

The art and the code are totally seperate things so you can use the art and have a closed source game so long as all the art is open source.

"I mean you must publish your game under GPLv3 and everyone else can modify your game and make money out of it? That didn't seams right to me."

Artists donate all this great open art and you want to use it for a closed game? Maybe that doesn't seem right to me.

Free/Libre art and code is important to people like me. We hope that you "Share Alike".

But yes, you can mix proprietary code and CC-BY-SA art as Botanica says.

Please be aware that while you can do it, its important like Clint said to have the code and art open.

Using By-SA assets with closed source code is kind of a complex issue, if I remember the various discussions I've seen on it correctly (the question being, in essence, what constitutes a derivative work that needs to also be licensed under By-SA).  It's terrible that this is such a point of uncertainty, but there you have it.  If I were you, I'd stick to CC-By and under for a proprietary game.  That's how I license most of my work because I want indie developers to be able to use them without issue.

The world of Libre/Open licensing can be a bit confusing. But the two licenses you are required to release under for the art jam do not restrict commercial use. Here's a simplified, human-readable version of the CC-BY-SA license :https://creativecommons.org/licenses/by-sa/3.0/. The GPL is quite complicated, however.

Make note that both of these licenses are Copyleft, meaning that whilst free to use and modify the art, by redistributing a modification to someone you grant them the same basic rights. So if you take some of the art and modify it, the community will be allowed to use your modification as well.

Also of note is that, the LPC just requires these two licenses so that someone can use them under either terms, but an artist is allowed to make their art available under different combinations of terms. So basically, people making this stuff COULD be convinced to release it under the non-Copyleft CC-BY for example, or will do so themselves, and then people wanting to use it under either the GPLv3, CC-BY-SA, or CC-BY will be allowed to pick which of these licenses they use it under.

The point is, the community has explicitly allowed you to use this art for commercial gain by offering the work under these licenses, but unless they also release it under CC-BY or you can convince people to, your modifications are also freely usable, for commercial gain.

Oh, and code and art are generally considered seperate and the license of one non-influential to the other, but as Redshrike said, there can be confusion at times.

Hopefully this will help your understanding and possible future usage of Libre/Open works.

"Using By-SA assets with closed source code is kind of a complex issue, if I remember the various discussions I've seen on it correctly (the question being, in essence, what constitutes a derivative work that needs to also be licensed under By-SA)."

That's not quite right. There is indeed the question as to whether the CC-BY "share alike" applies to the entire work. But even if it does, I don't think there's any requirement for the work to be open source - after all, CC BY SA says absolutely nothing about source code (since it's not intended for that). You could still use with with closed source, but it would have to be freely distributable, and allow people to build derivative works (including commercial use).

Clint Bellanger:

"Artists donate all this great open art and you want to use it for a closed game? Maybe that doesn't seem right to me."

No offence, but why should he care about what seems right to you-- unless you created the art?  What the artist who created the work wants -- as communicated by the licenses he released the art under-- is what matters.  You can root for your free code/art all you want, but it seem disingenuous to me to imply that he would be taking advantage of artists-- if he used the art in ways the artist has specifically authorized.

I think assuming that the artists would prefer the work to be used for free games isn't unreasonable.  It's true in my case, and I did the majority of the current artwork for LPC.

IANAL, but I take the intent of By-SA to be applied to the output of a game (i.e. video, audio, images, screenshots, etc.), and not necessarily the code or the engine itself - basically, that derivative works are those which actually incorporate the asset, not necessarily everything in the same project/folder.  The real stickiness of By-SA is apparent when you wish to mix it with other assets of varying licenses: say you have a CC0 background, a CC-By-SA sprite, and a CC-By-NC audio track.  The sprite's licensing demands that, for example, any video (say, a trailer on Youtube) produced using all three assets be CC-By-SA itself, which the audio track's license doesn't allow.  I would think this includes the output of a game while it's being played, as well - the derivative work is what's being displayed on your monitor and from your speakers while the game is running, not just when you save it to disk.

Under this scenario, neither the code nor the executable itself need to be openly-licensed at all - it's just the utility doing the remixing, and not the derivative work itself.  I guess the biggest hole in my assumptions would be situations where the art resources are actually compiled into the executable - that truly would be a work itself derived from the code AND the assets, in a sense.  The discussion on FreeGamer a while back covered a lot of ground on this topic (application of copyleft to hard-linked assets vs. assets invoked via a scripting layer, etc.).

"I mean you must publish your game under GPLv3 and everyone else can modify your game and make money out of it? That didn't seams right to me."

Have you read the license in question ? While IANAL the license explicitly says that if you take the code and make improvements you have to share the improvements.

Now on the other hand, you are saying somebody can steal your code, well it can be, if it was true then there wouldn't have been any other code than MS-Windows, no Ubuntu, no BSD nor any other kind of software.

Also think of what the Id Tech guys who keep releasing their code (Doom 3) if what you say is true then shouldn't have done that. In fact if you look at their history you'll see they have had a nice history with FOSS.

See https://en.wikipedia.org/wiki/Id_Tech_4

Also see http://arx-libertatis.org/

0ad is another one that comes to mind.

I am not going to give the answers but you should definitely you should check out why these people are doing these things. They should be benefiting somewhere otherwise they wouldn't have open sourced, right ?

Except they release long after their product life cycle.

@Vaughan, what about the source code releases with humble bundle, some of those games are now in GNU/Linux distributions.

There's another pot in the kettle, about the stealing bit. Apparently, Angry Birds - the game was 'influenced' by another game maker. The only thing was the developer didn't think it will be this big a hit (lone developer) so he kinda put a demo up. That demo was enough for the team which made Angry birds even though NO CODE was SHARED.

Also see this https://en.wikipedia.org/wiki/Category:Formerly_proprietary_software

There are a few entries which are still not there.

Anonymous posters seem to tend toward the silly. (S)he wants to license a work on his/her own terms and then says it "doesn't seem right" when others want to do the same.