Overall, not a bad deal for $18.99 (full game plus $20 in DLC).
Description of DLC.
Experience Halo Wars in a whole new way with the Strategic Options Game Add-on. Three new game modes will require players to re-think their entire strategy and approach to the game. The modes include: Keepaway – capture the flag style game; Tug of War – who can field and maintain the strongest army; and Reinforcements – adapt your tactics as you are granted waves of troops.
Expand your Halo Wars experience with the Historical Battle Map Pack Add-on. These new maps highlight key turning points in the epic war between the UNSC and Covenant forces. The maps include: Blood River – battle a single opponent over a treacherous natural chokepoint; Barrens – engage your enemy in the midst of the Flood; and Memorial Basin – two vs. two team play in one of the bloodiest battles in Halo history.