Here's the Official Blizzard Fan-Site Kit (English)...
Two decades have passed since the demonic denizens, Diablo, Mephisto, and Baal, wandered the world of Sanctuary in a vicious rampage to shackle humanity into unholy slavery. Yet for those who battled the Prime Evils directly, the memory fades slowly and the wounds of the soul still burn.
When Deckard Cain returns to the ruins of Tristram's Cathedral seeking clues to new stirrings of evil, a comet from the heavens strikes the very ground where Diablo once entered the world. The comet carries a dark omen in its fiery being and it calls the heroes of Sanctuary to defend the mortal world against the rising powers of the Burning Hells – and even the failing luminaries of the High Heavens itself.
If you've been holding out hope that Blizzard would cave in and offer an offline mode on the PC for Diablo III with its Reaper of Souls expansion, don't hold your breath. A recent dev interview really put the kibosh on that idea: Lead designer Kevin Martens stated pretty clearly that dividing the community into online and offline groups is not now, nor will it be, in the cards. When asked about the offline mode in Diablo II, he pointed out that the community back then was very unhappy about that division and added:
"That was the wrong choice to allow people to play offline, and we still stand by that. And we think Internet access is widespread. If someone has no Internet access, then yeah, Diablo III is not the game for them."
In the interview, Martens and Art Director Christian Lichtner also talked about the direction of Diablo's IIIand the game's economy sans auction house -- notably, that stockpiling items before the change won't give much of an advantage because the post 2.0 patch economy will be full of new items that can be acquired only through play.
Closed Beta of Reaper of Souls has been released as of Nov 20.
Reaper of Souls adds a number of new features to the core gameplay of Diablo III. These include:
The pre-expansion patch includes:
Due for release in 2014, same time as the pre expansion, Patch 2.0.