First off: NEW TIMELINE.
In order to sell the new canon as something unconnected with what came before, there'd be only a few familiar faces from the old: there must always be a Dracula, and there must always be a Simon Belmont. The second game would probably be a
competent and
not-lazy-DeviantArt-fanfiction rendition of Castlevania Legends to serve as the origin story and update Sonia Belmont's character into one notable for reasons other than "being a chick" and "being non-canon". Her son would be called Trevor, but he doesn't get his own game, and his only role is that of Simon's ancestor in lore. Alucard is not in this timeline at all. One of the games would be titled
Resurrection with a plot that echoes the major beats of what the original game would have had, but make it less goofy and more Mary Shelley: Victor Belmont refuses to take up his legacy, prompting the Church to do arcane rituals to summon back Sonia Belmont to mentor him back to the hero he's meant to be.
I'd probably stick with the Metroidvania style, featuring the fluid Igavania movement system, but with Lords of Shadow's flashy combos and Mirror of Fate's emphasis on blocks, counters, and dodges. No reason to fix what ain't broke, right?
Have a plan for at the very least six games, each one starring a different Belmont running from Sonia's tale (moved to 1477 to coincide with the real Vlad Tepes' historical death). That gives us three reimagined Belmonts (two of which were never prominent to begin with and are therefore RIPE for reinvention) and three new ones, and the fans would simultaneously get assurances that --
heh-- the sun ain't going down on the franchise here thanks to that long term plan.
There'd be a lot less emphasis on having a definitive canon, with Dracula in particular being portrayed in broad strokes and his origins being given several contradictory theories over the course of the games with none confirmed, leaving it to players to decide on what they think happened. The Belmonts would have a much more clear-cut history though.
The art direction and character design would be done with an eye for historical accuracy, being both historically and regionally appropriate (this is one thing that has always pissed me off about the series thus far), and the environmental and monster design would take visual cues from Dark Souls and Bloodborne.
The games would be fairly easy by default for accessibility by all skill levels, but also feature adjustable difficulty that could take things up to a truly punishing level, with AI becoming more aggressive and more inclined to use group tactics against the player at higher difficulties.
The climactic game would take place in 1977, partially to give the saga a span of exactly 500 years (more than enough time to play around with), but mostly just so I can drop silly references to the
rather ignoble three final Hammer Horror Dracula films. It would also finish on a definitive ending with no possibility for future stories past that point in history. After all, every great story needs a beginning, a middle, and an end.
There would definitely be a few references to Lords of Shadow and the old Classic timeline, but nothing substantial enough to encourage people to try to link the new with the old. Most would be pretty obscure references for lore hounds. Much more common and more easily found would be references to other works of Vampire fiction such as
The Horla,
Good Lady Ducayne, Carmilla,
Varney the Vampire,
The Night Stalker, Dark Shadows, and others would be in abundance. Probably a few anachronistic Buffy references as well because why the hell not.
Basically, Castlevania as a celebration of everything that the series has been so far, and a celebration of vampire fiction as a whole.
I can't think of something more appropriate to do as a rebooted series.