Warhammer 40,000: Space Marine 2 Message Board  

until horde mode formally comes out i found if you do operation 2 (the hive tyrant one) you can turn game into your own horde mode when you get to the bridge for the first time.

game objective is to detonate it to kill the hive tyrant... however if you ignore this endless enemies keep coming at you. makes for good mindless killing in emperors name!
and a good way to farm the 40k kills achievement also