This D&D module is so engrossing and I remember when I first got my hands on it....
May father was stationed in Spain, at Torrejon Air Base outside of Madrid in the Late Eighties. Two of my older teenage sisters were classmates with the boys that lived in the home above ours - it was base housing for service members and their families. The brothers had a stack of D&D modules and Ravenloft was one of them. The B&W art inside is spectacular and the fold out castle even better! My sister borrowed the book and she read this module to me, the vivid descriptions of the forlorn fortress and the terrified countryfolk intrigued us so much, this "game". I remember that one of the boys had used colored pencils to hue the B&W pictures: some zombies were putrid green and some of the vampires pale blue.
I believe that this is fondly remembered because the creators poured so much intelligence and wit into the adventure. Even to my young mind, I could tell it was inspired by other works, yet it's a creation all its own. A roleplaying accessory full of mystery and monsters. It sort of spoiled me because after discovering this module, I wanted to read any other I could find. Not everything is created equal, and D&D modules are the same way. Most other adventures were no were near this entertaining, but there are some.
This module and its "effects" have been a consistent moneymaker for the D&D brand. The current edition, the 5th, has a version of the story, the tragic tale of Strahd and the party of adventurers that meet him at haunted Castle Ravenloft, and it's arguably the best example of how great Dungeons & Dragons can really be. If you can find this old module, you won't be disappointed in what you find inside. Heck, the newest version is just as good!