I am not a lawyer, but the consensus appears to be that Creative Commons licenses only apply to the art itself, not bundles of it such as a game. Of course, for that buyers of your game would need the ability to easily extract and reuse the CC art from the package you sell. So I guess the latter option.

As for dual licensing, that means you can apply either of the licenses, whichever best fits your project.

That is actually the opposite of what CC says, they say that the code is a derivitive work, however the consensus of other people is that it is not.

@kmcconaughey: You are wise to ask about this and it's good you're getting all your ducks in a row. However, that particular question about CC BY-SA has been discussed many times before:

http://opengameart.org/forumtopic/help-with-cc-by-sa

http://opengameart.org/forumtopic/cc-by-sa-and-apple-licensing-incompati...

http://opengameart.org/forumtopic/license-question

http://opengameart.org/forumtopic/how-to-use-licenses

http://opengameart.org/forumtopic/licensing-questions

http://opengameart.org/forumtopic/cc-by-sa-30-with-unity3d

http://opengameart.org/forumtopic/anti-drm-waiver

http://opengameart.org/forumtopic/oga-licensing-suggestion

http://opengameart.org/forumtopic/new-license-proposal-in-response-to-dr...

I am not saying "don't ask this question any more, it has already been discussed."  I am saying, although there is a general consensus, there is unfortunately no difinitive answer that covers all project situations or art assets you may be interested in.

You may have to do quite a bit of research and then come to your own conclusion. To be safe, you can always ask each artist if they are ok with what you have in mind. The point of licenses is so you don't have to ask the artists what is ok and what is not, but the question you rase is a sticky one, so it's best to be sure if you can. 

Failing that, only an intellectual property lawyer could really give you a solid answer. Even then, an IP lawyer could only give you advice about your specific project and the select assets you are interested in using.

Best of luck. :)

I've heard people here say that all ART here is available for Commercial Use. (I will credit the appropriate people) Is this true?

Yes.

But commercial use doesn't mean "credit the appropriate people".

Read the relevant license and understand it before using anything so that you can make sure that you are meeting the requirements of the license.

If something has 2 licenses or more, you can pick any of the licenses. People putting both GPL and CC BY-SA is beacause of some projects only accepting GPL-compatible licenses (no CC license except CC0 is compatible with GPL).

CC BY-SA is weak copyleft, the license terms aren't “viral” in any way.

Remember that all CC licenses except CC0 have a “no technological restrictions” clause, which prohibits measures that would prevent users from exercising their rights.

@MedicineStorm. This is far from a cut and dried issue, as evident in the number of threads and the length of those threads. Unfortunately, the wording that makes those licenses legal also makes them difficult for the average user to fully grasp. Licenses are also vague to cover the largest audience possible. This leaves a lot to interpretation, and unless you're also a lawyer this can be daunting.

@cdoty: I... agree. :? I guess i'm not sure why this was direct at me? Are you just confirming what I said?

@MedicineStorm: I guess the threads really don't offer answers; they demonstrate that there is a lot of confusion regarding licensing. They leave a lot to interpretation and are pretty daunting. Most of the thread is posts about how people interpret the license.

@cdoty: you're right. I should have offered a direct answer. Sorry.

@kmcconaughey: As long as you make the artwork availbe like in a file in the game files you should be fine. BUT, some would disagree. I'm not a lawyer and you'll ultimately have to decide for yourself, but this is my opinion. :)