It had several innovations for it's time
- A strong, central villian whose history and motivations were mapped out rather than being "just a stat block" with at best a name attached.
- A villain who moves and reacts to the player's action rather than remain in one static spot
- A method of randomizing aspects of the adventure, allowing for
- A stronger story/plot than adventures tended to have at the time (any story was usually "how you get there" and there was relatively little plot beyond "explore everything, loot the bodies, kill the enemies and solve a couple puzzle/traps along the way".) The interaction of Strahd/Tatyana/Sergi and how the players got pulled into the triangle was an entire story subplot in the adventure.