I have already finished campaign. Basically there are 3 races. Empire that is kinda classical human race with elves and gnomes. Easy to play. Then there is Beast race of tribe like beings that have allies like goblins, trolls and lizard men (orcs are surprisingly out of this group). And last are Fallen that are like Zerg+Warcaft undead (insect units, build on deformed land, summon buildings...) that have deep elves as allied units.