The whole of Tamriel! That's what The Elder Scrolls Online will contain, so you'll be able to stride your way through Morrowind and shiver your way through Skyrim. Disclaimer. The whole of Tamriel except for the bits that are going to be chopped out to make room for expansions and Skyrim won't be as detailed as in Skyrim: The Game of The Place. A lot of Tamriel then. There's a great deal of player on player action promised, although no NPC marriages. Oh, and you can become the Emperor. What else can be learned from an American magazine's leaked coverage?
It'll be a World of Warcraft style game. That's not based on an analysis of the facts and careful comparison, that's based on the fact that it's described as having World of Warcraft-style mechanics. Toolbars with skills loaded onto them, third-person perspectives for all and a concession to classes and levels. That said, every player will apparently be able to develop a broad range of skills, as well as having every guild in the game open to them.
There's a big emphasis on exploration, with dungeons, caves and entire quest lines hidden from view until a player stumbles across them, rather than being referred to by an NPC, marked on a map with a big 'X' and then pointed to a bloody great floating arrow. That's how most things will be handled but there will be actual discoveries to make as well.
As for the plot, it's 1,000 years before the events of Skyrim and, wouldn't you know it, a great evil is rising and three factions, each containing three races, are trying to stop it. While squabbling and warring with one another. So you've got your nords, dark elves and argonians in the Ebonheart Pact, high elves, wood elves and khajiit in the Aldmeri Dominion, and bretons, redguards and orcs in the Daggerfall Covenant. In between all the questing around, characters will be able to fight for the Imperial seat.
Here's a question: would you rather be a homeowner, a vampire, a werewolf or the Emperor? In TESCO (credit to @davescarborough) you can only be the latter. No vampires, no werewolves, no homeowners, just power-hungry leaders with little regard for the democratic process. It's a lot like the real world.
To become Emperor you'll have to conquer Cyrodiil, taking forts, mines and farms in many-on-many PvP scraps, eventually attacking the Imperial City and engaging in a 100 vs 100 battle, the winner of which becomes Emperor. Not all 100 of the winner, obviously, but instead the member of the victorious faction who contributed most in the conquering process. Not sure how that works but it could lead to some delightful arguments.
It's a shame that the whole Being The Emperor thing will apparently be for bragging rights rather than political power. The development team is the 250-strong Zenimax Online with Bethesda providing lore assistance but not actual development assistance. There are veterans of Dark Age of Camelot at the team and although I'm allergic to PvP, it's the faction against faction struggle for supremacy that has me most interested.
The rest sounds fine. It does seem an awful lot like WOW, although that doesn't hugely surprise me. A stamina bar that dictates how many blocks and dodges a character is capable of should make combat a little less like forming an orderly queue and the removal of aggro and claims of more interesting than MMO standard artificial intelligence could give fighting a different feel. There are also public dungeons, 'phased questing', which sees the world change for players involved in certain quest lines, and full voice acting.
There'll probably be an avalanche of details and screenshots any day now. There might even be an announcement of an announcement of a teaser trailer for a trailer.