Assuming you’re talking about making video games for money, this is probably a little bit beyond the paygrade of FEU proper. That said, a good place to start might be our credit guidelines. We do mention treating “F2U” (free to use) as CC-BY-ND which doesn’t include a non-commercial clause, but I’d suggest talking to your lawyers and probably the individual artists in question.
(To make things completely clear: FEU’s credit policy is intended for internal, non-commercial purposes. FEU as an organization exerts no control over the community asset repository. We make no official statement on the legality or commercial licensing status of any assets therein.)