Except that you're completely mistaken.
Ansem SoD not being AtW is not a retcon at all. I don't need to go into further detail for that one because you explained it well. Your error lies in what you think a retcon is.
Always understood it to be this:
Wikipedia said:
Retroactive continuity (retcon for short) is the alteration of previously established facts in a fictional work.[2] Retcons are done for many reasons, including the accommodation of sequels or further derivative works in a series, wherein newer authors or creators want to revise the in-story history to allow a course of events that would not have been possible in the story's original continuity
This is exactly what happened with the whole Ansem SOD =/= AtW situation.
It was taken as fact that they were the same person in Kh1. Then, in KH2, those facts were altered for "the accommodation of sequels... to allow a course of events that would not have been possible" otherwise.
A retcon is changing something that has already been entrenched in an antecedent story; altering what was previously established in a prior installment. This is why retcons are considered forms of poor storytelling for the most part; no one would complain about them if that wasn't the case.
Take for example what you said about Roxas' reasons for leaving Organization XIII. That is a retcon, not a plot hole.
It was originally stated that Roxas left the Organization to find and try to meet Sora.
In Days, he leaves because of Xion. Also, he completely hates Sora at that point because he wants to be his own person.
That's not altering fact. When you alter something, it's still what is. This is completely making what was fact completely false.
I'm going to give a cruddy example here, but for the sake of argument, bare with it:
Say that a Scientist discovers that Oxygen doesn't do anything for the human body and that just the action of breathing is how we live.
Now, Oxygen giving us energy is accepted as fact. But, now, because of that Scientist's discovery, it's not. The fact wasn't altered, it was completely proven false.
A plot hole on the other hand can be a contradiction as well, but it's in a different context. Part of the difference is that there are different forms of plot holes -- a contradiction of an event or statement is only one of them. Whereas there is only specific type of retcon.
Contradictions are only plot holes when it happens in the same installment, not within two different ones. This is why you never hear of retcons being made on the first game of a series, or on stand alone stories of any medium; only plot holes, if there is any to begin with.
Okay, you're right on this part. There are different types of plot holes.
But, that doesn't really change anything about what I said since contradictions are a type of plot hole.
