In case of false expectations, it's not remotely Dungeon Keeper 3 - there are obvious similarities, but some major differences too.
As I understand it, rather than killing the invading heroes, you want to butter them up by providing a stream of mobs for them to kill, treasure to find and scary dungeon decorations to titillate them. Once they are full of heroism, you capture them, torture it all out of them, then release them (you can kill them, AFAIK, but you don't get as much "currency").
It's more like a Sim-ThemePark/Dungeon, really. Still looks good, but don't go in expecting DK3 or you'll likely be disappointed.