User blog comment:DE-Note/RWBY Game idea/@comment-32598036-20150804014542/@comment-25555436-20150805230528

I wasn't recommending the FOX engine for this anyway.

Do note that in a fighting game, most of the physics granted by the engine will go to the environment, and the clothing, hair, and maybe special effects. The actual air juggling part is entirely unrelated to the engine.

As for graphics, neither work. The Unreal and Netherealm engines, graphics-wise, are both geared more towards more realistic visuals and models. RWBY, however, isn't at all realistic, and the characters and environments and pretty much everything look less like realistic models and more like painted manikins (Which was the intention, of course).

I've already seen a picture of Mario, under the effects of the Unreal Engine. A bit out of place. And even then it doesn't mean it would work with RWBY, for Mario's models and environments are in a different area than RWBY's "drawn-on, painted-on" style.