Diablo III Lore and Art Q&A

The guys over at Joystiq had the opportunity to quiz Blizzard's Leonard Boyarsky and Brian Morrisroe during the WWI event about Diablo III's lore and art direction. The Q&A is actually broken into two parts, the first of which recaps their panel discussion and a second portion that contains the Q&A itself.
The story of Diablo 3 is set twenty years after Diablo 2: Lord of Destruction. (Warning: spoilers from Diablo 2: Lord of Destruction to follow!) Deckard Cain is convinced Hell will invade at any time because of Tyrael's destruction of the Worldstone and feels guilty for not having better read the signs. What happened to Tyrael (who hasn't been seen since the worldstone was destroyed) is unknown. As the invasion hasn't come, the events of Diablo and Diablo 2 are seen by the populace as legend.

On the art side, Blizzard's philosophy is: stylization over realism, strong silhouettes, don't be afraid of color, dynamic animations, support the gameplay, and make it epic. With Diablo 3, they started by going back to Diablo to identify the strengths of its style: an emphasis on horror. They then moved on to Diablo 2, which succeeded by expanding on the original and introducing lots of new areas. Said Morrisroe, "Our memory of what Diablo and Diablo 2 were was a bit different than the actuality of it. Visually we were remembering it as more of a dark, colorless game, but there was a lot of vibrance."

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Q: In the end of Diablo 2 we went to hell, killed him, smashed his Soulstone and essence of him, Bael, Maphesto ... how do we justify him coming back?

Leo: You don't know for sure that Diablo is coming back. [Ed: ... !] We don't want to divulge too much of the story, we just want to say that it will be entertaining when you come to it.

Q: In previous game you had quests to achieve to get, say the Horadric Cube. Will there be similar quests? Will we be able to get the Horadric Cube again?

Leo: The way the process works is we look into the story, look into the lore, and we want that to drive the gameplay and drive the quests. I can say there will be quests related to lore. In Diablo 2 they didn't just set out to say "let's make this great cube," it came out of the design process.