Kill a zombie using an environmental hazard in any game mode

Complete an entire arena, getting every kill with the Chainsaw

Kill at least one zombie with each weapon type in any game mode

Kill 10 or more zombies at the same time in any game mode

Play in an online multiplayer game

Complete each arena at least once in the same game in any game mode

Rack up a 100x multiplier in any game mode

Save 25 survivors in any game mode

Kill 25 zombies in any game mode using environmental hazards

Complete 7 days in any game mode without dying

Complete the final day of the "7 Days of Hell" unlockable mode

Complete the Final Day, in either Single or Multiplayer, and finish the game