IGA did not create the story nor is it his. He merely continued what others had started or else he would have done his own CV timeline without including the original games that he never made.
I already thought this would hit a sore spot with some, heh. Personally, I think IGA created the storyline in the sense that he unified games that were never supposed to be linked (CVA and CV3 etc.), and actually tried to let it stay consistent afterwards.
I'm surpised some people are saying "I can't see Castlevania being like Final Fantasy", but before 1997, that's exactly what it was. I'm not sure if everyone read the "Akumajo Densetsu fan interview" thread, but something that became evident of it, despite being disputed by some, what that CV3 and CVA were both mutually exclusive games that both were the definite prequel to CV1. Also, there's no way CV4, Haunted Castle, Vampire Killer etc. were ever supposed to be in the same continuity. This was just something IGA came up with after the fact.
If the series would go into "not caring about continuity mode", it would revert back into it's natural state.
I'm perfectly fine with gaming series that have one unified continuity, but that's not what the developers want. Otherwise, we never would have gotten Circle of the Moon, The Arcade, the Pachislots, Lords of Shadow, CV4 when we already had CV1, Adventure Rebirth when we already The Adventure, etc., etc.
I also disagree more that one continuity would mean no sense of history. It can still be done. Shin Megami Tensei for example, has several sub-series that one their own already created decently fleshed-out worlds (Devil Summoner, Persona), but also connects everything on a meta-level in a subtle, but interesting way. Every world is connected through the Amala network, and events in one world can affect another. Not that Castlevania would need that much of a connection between continuities, but sometimes small references here and there and a few cameos do the trick. Heck, Final Fantasy itself even has the Void which links each game's world together, and Gilgamesh, who is basically Mr. Continuity Nod.
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