Interesting idea. Nosferatu? Check. Castlevania? Check...but I'm wondering, why not use the 'Symphony Of The Night' score, which is generally regarded as one of the best game soundtracks ever?

Incidentally, this film has been re-scored 12 times since Hans Erdmann's original score - so I think your idea fits within this tradition.

At the Toronto Internation Film Festival in 2000, I saw a pristine print of Nosferatu with a live symphony orchestra playing Erdmann's score. You haven't seen the film until you've seen it this way - it was incredible.

Good luck with your project, I shall be eagerly following.