I doubt Chinese will ever see much use outside of China. 5% of the world will never be able to speak or understand it. It's a tonal analytic language, so the tone deaf cannot hear the difference in sounds. And that's without considering that it has a ridiculous written language non-natives have a terrible time with.
Japanese, on the other hand, is an atonal synthetic language, which makes it much easier for the rest of the world to understand. It also sounds nice, while Mandarin sounds frikking disgusting. It's loaded with nauseating sounds. As in the sounds you make when about to throw up. Tonal languages are loaded with gross sounds, and I hate them. Norwegian is just as bad with those swallowed g's. Yuck!
There are a number of Japanese bands that sing entirely in English. I don't know if that would mean games in English would go over well or not. Probably bears no relation.