Epic when it first came out, one of the first, if not the first windows only game on the market. Also boosted a random map generator so every game was different. The original game idea was turn-based , think there is a demo out there somewhere. The original dev team made another game called torchlight which is also excellent.
David Brevik, creator of original Diablo left Blizzard somewhere at the end of Diablo 2 era and went to make Hellgate London and later Marvel Heroes. And yeah, first Diablo was supposed to be turn based game but they decided to go real time and boy were they right on that one :) I like Torchlight 2.