DoW dark crusade introduces 2 new races each with their own new stratrgys. the tau is one of the new playable races and the necrons the other which brings the total count of DoW playable races to nine(Space Marines, Orks, Eldar, Imperial Guard and Chaos).
2 new inotive races gives the DoW series a much more open strategtic depth as it allows player to use the tau's mixed range of powerful range combatants with a broad range of melee fighterswhich helps balance out gameplay as many tau range units have low health.
The necrons give you many new strategys. for example they have units that lower morale of enemys in their presence and a much more customaiable commader as he unlocks new upgrades with the base. the necrons also use a stratgys like the orcs by only usng power(unlike the orcs) but build obelisks that work like waaaagh banners bt on sp's. They can even resurect units.=)
it even introduces a new campain which is like a risk board.
overalll a must buy for all DoW fans and a very challenging campain sytem which makes you use ur brain alot more instead of just charging in.