I was thinking of a plot which, similar to Judgement involves Time reaper, who freezes the castle in limbo, void of time and space, he draws the power of Dracula and his servants gathering dark power over time, Trapping the souls of every hero that conquered Dracula, knowing that there would be no real opposition, Aeon and St. Germain team up to pluck worthy Descendents of each vampire slaying clan to restore the souls of the Heroes while gathering equipment and power-ups throughout time plus anomalies that have made it's way in.
The Castle now more alive, tends to shift it's shape rather quickly, making every navigation a meaningless exploration...
The play-style has a fair choice between Classic and Metroidvania style plays, If we can master the coding for both we'll have both
Classic - Linear areas, Stage progression
Metroid - One big map in sections, Warp points are permanent, though the rest of the map is entirely random