Greatest expansion pack ever? Maybe? one of the top RTS ever? Yes
Dark Crusade brings more factions into the Real Time Strategy than any other game and expansion has ever. 7 Diffrent races with little to NO similarity, and completley diffrent storylines behind each, including hero units which during campeign, grow stronger as you earn points to give them better wepons and armor.
Campeign is set up to be a conquest kinda thing where every turn you get, you try and take a territory, and when one of the other forces come onto your territory, you can choose to defend or let the computer try and do it for you, either way, every territory you take, you save your base and get to use the same one to defend against other attackers.
All in all, Dark Crusade is everything you got in the first two Dawn of War's PLUS some, infact, plus alot, its a very very rewarding game to own and it will keep you enthralled in the story mode and campeign for a very very long time. Enjoy hopping online and painting up all your new units!!