Warhammer 40K: Space Marine's free "Exterminatus" co-op DLC will kill in service to the Emperor on October 25, according to Eurogamer. The DLC includes two, four-player scenarios that pit the Space Marines (or "SPACE MARINES!" as is incessantly shouted throughout the whole game) against Orks and Chaos. Relic is reportedly working on more content for the game, which will be released as free and premium DLC sometime in the future -- certainly sometime before 40K.
C&P'd from http://www.joystiq.com/2011/10/07/warhammer-40k-space-marine-exterminatus-dlc-drops-oct-25/
Horde mode basically ! As a warhammer enthusiast as a kid ......Sounds good to me ! + you cant beat free dlc