You're basically describing 1st Edition Vampire the Masquerade. It you ever look at one of those old campaign books, or the first gen material, the systems are different, but the graphics and mechanics, and maps and monsters are straight up old school dungeons and dragons.
The monsters became more vampire-centric, vampire hunters, secret societies of clerics, magi and from there, vampire magi.
The real challenge is going to be presenting monsters, traps, and dungeons that are suited to the immortal. Drowning, poison, gases, and such are hindrances, and the real things that challenge them are going to be sentient foes, and things that kill regenerators, ala fire, acid, and specialized materials, focused magics, and organizations.