iPhone...no.
It's bad enough not everybody has an iPhone and spending money on it for that game would be ridiculous.
Sure it looks good, but IMO the gameplay would be odd.
I'd rather just have it on a regular cellphone or better if it set was on the DS.
DS would probably make things easier than a phone.
*steps next to Riku-Keyblade* Uh, rebel? *weakly lifts fist* XD
