To be specific, the "Share Alike" (SA) clause means that if you make derivative work of the CC-BY-SA artwork, then you should share this derivative work under a similar license. The general understanding is that a game using this artwork is not a derivative work, so in this case you only need to give attribution (BY). If you create new art assets based on this artwork though, then you should share it under a similar license. Your own art assets which are not derived from #NotZelda are not affected by this license, so they can stay proprietary.
