Four player co-op, mission structure, multiple costumes, create a character. Either pick one of the 11 different keyblade wielding styles that have been shown thus far or tie the wielding style to the keyblade itself. Big and unwieldy? Terra style. Two handed grip? Eraqus style. Short and speedy? Ven style. Two big blades? Valor style. Two light blades? Roxas style. Make the abilities item drops with a trading system. Let us pick classes too. So a mage would be play like Aqua, a tank would be like Terra and a DPS would be like Ventus. Make the mission structure like Days and give me the keyblade evolution of chi. Toss in some character trees to customize my character. For example, one tree leads to the ability to use drive forms, which you would have fight specific enemies to unlock (defeat X heartless with magic for Wisdom, X heartless with the keyblade for Valor, unlock Wisdom and Valor and defeat X enemies while used them to unlock Master, etc). One tree leads to keyblade transformations. One tree leads to limit breaks a la days. One tree leads to style changes. One leads to a redone overclock system. And you can switch between a KH1, KH2, and KH3D/BBS/re:coded magic systems. Story line is the plot of Kingdom Hearts χ[chi]/Unchained χ/Union X
