Blizzard tweets that yesterday was the 15th anniversary of the release of Diablo. Sure enough, Wikipedia verifies the first game in the action/RPG series was indeed released on New Year's Eve in 1996. Here's the tweet: "15 yrs ago today the fight against Hell itself began. Now with #D3 on the doorstep of 2012, we thank you for making this possible. #Diablo15."