It's likely on November 30, 1996 Diablo went gold, but definitely not the launch date. The date is taken from Wikipedia. Nigh Christmas 2006, Blizzard posted Diablo was going to be launched soon -- as seen in the first image below. That demonstrates there was never an official release date announcement. The original Diablo game shipped when it was ready.
Browsing through old Blizzard newsposts, I managed to pinpoint the following statements:
Blizzard Entertainment's Diablo In Stores Now
New RPG pushes multiplayer excitement to the limit by providing one-click access to free on-line gaming
IRVINE, Calif., Jan. 3, 1997 - Blizzard Entertainment this week shipped Diablo, the much anticipated role-playing game in which players enter a sinister underworld filled with supernatural forces and demonic creatures. The game is the first Blizzard title to take advantage of Battle.net, the company's new on-line gaming service which provides free access to multiplayer gameplay over the Internet.
Diablo transports players to a medieval village plagued with evil and darkness. In a quest for vengeance, the central character descends into a crypt and expansive labyrinth hidden beneath the village. Game play focuses on exploration, conflict and character development as players travel deeper into the underworld's demonic halls.
Diablo is available immediately in Windows95 CD-ROM format at most computer and software retail chains nationwide for approximately $50. The game is also available directly through Blizzard at (800) 953-SNOW.
Says Allen Adham, president and founder of Blizzard Entertainment, "Diablo offers gamers a new kind of role-playing game. The game boasts not only great fully rendered three-dimensional SVGA graphics never seen before in an RPG, but also unlimited replayability. Each time a quest begins, Diablo's random level generator creates a completely different labyrinth. With every game, players can expect to see a room, corridor, monster, trap or treasure in a way never encountered before."
Battle.net - Free On-Line Gaming Service Diablo is the first game to offer easy access to free on-line gaming. Players simply select the Battle.net multiplayer option, and they are automatically connected to Blizzard's free Internet gaming service. Once logged on, players can compete head-to-head against players from around the world. Blizzard charges no hourly or monthly fees to connect to Battle.net. In order to play via Battle.net, access to the Internet is required, and players are responsible for applicable on-line access fees.
Blizzard Entertainment has teamed with Primenet Services for the Internet and other Internet service providers to put Battle.net online. Primenet's fully meshed ATM (Asynchronous Transfer Mode) network offers the high-speed, low-latency Internet connectivity essential for online gameplay.
Product Overview As the central character in Diablo, players must explore a dungeon hidden beneath a desecrated church in their village. As players encounter 16 levels filled with corridors, traps, weapons, magical items and demonic creatures, the truth about what evil force decimated their village begins to unravel.
Three unique characters types allow gamers to play as a brave Warrior, a cunning Rogue, or a mysterious Sorcerer. As characters venture deeper into the labyrinth, they discover weapons, armor, and magical treasures, and develop their character's skills and abilities.
Players can either approach Diablo as a single-player game, or as many as four characters can play using the game's multiplayer options. In multiplayer games, characters can play both competitively and cooperatively.
Key features in Diablo will include:
Sixteen levels of demonic horror filled with traps, treasures, magic, weapons and monsters. A level-generation system that randomizes dungeons, creatures and quests to maximize game play. Multiplayer option that supports as many of four players via network and Internet. Head-to-head play supported through direct link and modem. Seamless one-click access to free on-line gaming via the company's Battle.net service. Real-time engine allows for intense exploration and exciting battles. More than 100 different monsters and creatures varying from skeletal warriors to the undead and demonic horrors. SVGA enhanced graphics, 3D modeled characters and real-time lighting effects with rich three-dimensional rendered scenes.
Best known for the number-one selling Warcraft series, Blizzard Entertainment is a premier publisher of entertainment software, and a division of CUC Software, a wholly owned subsidiary of CUC International Inc. (NYSE: CU).
Eldorian and I have been discussing the anniversary since yesterday, and we found in wikipedia the inaccurate November 30 date. The discussion came to be because, as Eldorian suggests -- the Diablo anniversary date might be a very attractive date for Blizzard Entertainment to announce officially the release date of Diablo III. This is, of course, speculation. Yet, it's a tempting date to keep watch over.
I take the opportunity to announce that Insight Editions will provide Blizzplanet 10 copies of Diablo III: Book of Cain. Stay tuned to Blizzplanet. We'll giveaway two of them each week over the next five weeks.