Hey can you do me a favor? I've been interested in that exact phone, but the only way I'll buy it is if it can play Chaos Rings without the glitched graphics.
Can you go to the store and download the free demo of Chaos Rings? Once you get to the very first battle you'll be able to see whether the models are all blacked out or not.
It's a huge download, but if it all works out, I'll be trading up from my Lumia 635 to that 638!