Extreme Firefighting
Not unlocked yetSet 5 enemies on fire and then kill them with explosives.
Out of honey? Chew bees!
Not unlocked yetSurvive 5 waves using only your fists and legs.
Complete a set
Not unlocked yetDuring a single round kill an Infected, Suicider, Ram, Butcher, Floater, Walker.
Looking for trouble
Not unlocked yetSurvive 5 waves in each of the 4 Arenas.
Stick it to the enemy
Not unlocked yetSurvive 15 consecutive waves using the analog combat controls.
Gladiator school
Not unlocked yetSurvive 15 consecutive waves with each of the 4 characters.
Fancy
Not unlocked yetSurvive 10 consecutive waves using only custom weapons.
Morituri te salutant
Not unlocked yetSurvive 30 consecutive waves with at least one co-op player.
Death Incarnate
Not unlocked yetSurvive wave 30.