Killing Floor: Calamity (2014)

Killing Floor: Calamity takes place in the devastated cities and countryside of England, after a series of cloning experiments for the military goes horribly wrong. You know how this works - your mission is to survive waves of Zeds and take out the Patriarch! Believe me - the action is furious and relentless! 2-player co-op couch gaming, multiple difficulty levels, 7 Perks upgradeable to Level 20 (with new special abilities, too) and 9 brand new maps for the OUYA.