It's important to note that Games Workshop is not only fully supporting the project, but GW writers are crafting the campaign storyline. The campaign can be played from either the Empire or Chaos perspective. The Empire campaign details are still being hashed out, but in the Chaos campaign, the idea is that Chaos is gearing up for a second Incursion into Empire territory -- your main hero is a budding Champion of Khorne, whose goal is to become a fully fledged Demon Prince as the campaign continues.
On the turn-based tactical map, which looks amazingly detailed with familiar Warhammer locations such as the Black and Middle Mountains clearly identified, you spend money to build armies which are then moved across the map. Unlike Total War, though, there are several random encounters that pop up that force you to make a decision -- for example, you may run across two Skaven clans fighting a battle, and you can either ignore the fight all together or choose sides, hoping that if you win, you can "encourage" one clan to join your cause. Nothing is forced on you though, so you may move your armies freely about the landscape, even ignoring key campaign events if you so desire… although waiting too long to stop a mass Empire attack or sitting on your thumbs as the hordes of Chaos spill into the Empire from the north isn't advised, but the option is certainly there.
The game sports four races which you can use to build your main army group: High Elves, Empire, Skaven and Chaos (Khorne Chaos to be specific). However, dwarfs, undead, orcs, goblins, trolls, ogres and other Warhammer races are available as freebooter mercenaries, so even though you can't field a fully fledged dwarf army, you can at least use the little guys to help bolster your forces.
