Been working on this, maself! After some consideration, one of the bigger challenges was the passage of time. Vampires are ancient and live for centuries, feuding, setting complex plans in motion, then letting the gears run for decades. It was realllly important to me that this be meaninfully manifest through mechanics, this building of the machine of your legacy, then winding it up and letting it go. I’ve been looking to Blades in the Dark and Undying (PbTA) for a lot of inspiration in a few key areas: Factions, clocks, broader-reaching Fortune rolls, blood as units of power, maintaining humanity, the rhythm of “zooming in/out” between phases. I see three “zoom” levels:
1.) Chunks of weeks or months where players choose ways in which they build and consolidate their own power, begin alliances, and develop their legacies.
2.) The moment-to-moment where crucial decisions are made, where vampires chase their quarry, or other world- and character-developing activities.
3.) Spans of whole generations where the machine of your design runs, determined by Fortune rolls (taken from Blades) where dice rolls determine the effect of the plans set in motion. Rolls are augmented by choices and results occuring in 1 and 2. The GM interprets these results, shares the span of time that occurred, and sets the stage for the next “round”.
I’d also borrow Crew development from Blades (with “Crew” being replaced with “Clan” or “Family”), showing paths for how to increase your clan’s power.
Obviously this is just a skeleton, but the premise of seeing the progress from your origin (when you turned) to establishing power, playing by a different set of rules as the human world changes through conflicts, trade, the Rennaissance, the Industrial revolution, across countries and continents, etc., is immensely satisfying to me (it was why I was fascinated by “Interview with a Vampire”).