Not only had this game revolutionaty gameplay but also a very original story that still stands completly unmatched.
There are no dialogues in this game and there are no FMVs or cut-scenes, the story is told at very few occasions in the game either by a certain character in town named 'Cain' or when the player read books in the dungeon. But it is not the amount of story/dialogue a player has to plow through that makes a game good, its the quality of the story.
A good part of the story is actually found in the manual, there are several pages of story there which makes the player already familiar with the world when you start playing.
The story takes place in the mortal world on the edge to the realm ruled by forces of Hell. I dont want to give away any part of the story but this is not the standard cliche-cheesy story *cough* Final *cough* Fantasy.
Blizzard has truly succeeded in creating a dark and gothic medieval world. The music, the mood, the language, the setting, it all contributes to the immersive atmosphere of the game. Also, the characters and the monsters in this game are very well made and not cartoonish like they are on many other games (like Diablo II).