[quote=@mattmanganon]
[@Sadu] His plan changed from game to game.

KHBBS: I am Xehanort and my plan is to brainwash a bunch of kids to make a X-Blade that will let me restart an ancient war that i have no idea who it was between or what it was over... That failed, my new plan is to kill myself and let the next 2 of me figure things out.
KH1: I am Ansem, i want to use the power of Kingdom Hearts to take over the World
KH358: I am Xemnas and i want... You know what, nobody gave a fuck about this game.
KH2: I am Xemnas, i'm gonna make my own Kingdom Hearts with blackjack and hookers.
KHDDD: I am Xehanort and i'm gonna use time-travel and shit to revive the 13 guys you didn't give a shit about in the last game, because Nomura is literally just flinging shit at the wall to see what sticks.
KHREC: Nothing happens
KH3: I'm Xehanort and turns out every time that you defeated me before WAS ALWAYS PART OF THE GRAND DASTARDLY PLAN TO CLONE MYSELF 13 TIMES in order to restart that war that i still know nothing about, because... I still don't fucking know. Also, apparently i'm a tragic good guy now? Also, apparently the guy with the eye-patch was the REAL bad guy all along.
[/quote]

I have a protest, and something that will either shed light, or make everything WAY more confusing.

One: I played Days and liked it. Though, his plan is the same as it is in 2, save the fact that he's trying to make his own keyblade wielders to do it.

Two: The Keyblade War was something in Union Cross. In a nutshell, during an age where Keyblade wielders were about as common as flies in a dumpster in August, this guy called the Master of Masters decided to kill primordial darkness. To do that, it had to possess someone, then you had to kill that someone. There were thirteen of 'em, too. So, he tried to make as many of the keyblade wielders as he could fall to darkness, then pit all of them against each other. He got himself sent to the Shadow realm doing this by breaking laws of reality like Sora did in Re:Mind to help orchestrate this. He had his best student, a guy called Luxu (Later Braig, even later Xigbar) take his Keyblade (No Name) and make sure it ended up in the hands of people who could complete his work if he failed. He only kinda succeeded, the war and it's aftermath either killing or trapping around eight of the thirteen darknesses.

(TL;DR - The war was something orchestrated to kill primordial darkness. Xehanort restarting the war is him trying to get himself and others possessed by primordial darkness, then killed. Xigbar is really a guy called Luxu, who technically is the real owner of No Name.)

TL;DR v2: It's all a really confusing knot that is addressed in games that are prequals to the prequal.