I'd make the boss of the game a god and then no matter what you always lose the end boss battle. Because I want all those hours you just wasted to form a nice and neat line and one-by-one bitchslap you until you cry.
Seriously i'd just bring back good story telling and either bring back turn based combat or make a more badass version of Kingdom Hearts' combat system... with blood. For the love of god, when ifrit rises from Hell just to tear you apart and light you on fire, I want to see you bleed and roll around on the floor screaming. And i will count my experience points after taking a healthy inhale of your burning flesh as that putrid charred smell wafts through the air.