In an On-line Coop game, revive another player and make sure they do not receive any damage for 15 seconds afterwards

In an On-line Coop game, perform your first revival

In an On-line Coop game, hold out until wave 21 in Factory Barricade

In an On-line Coop game, kill 20 bosses with your team in a single game

In an On-line Coop game, kill a boss with a melee weapon

Host and play an On-line Coop game

In an On-line Coop game, upgrade a sentry gun to a weapon station

Pick only four perks: Fire Starter, Friendly Fire, Remote Detonator and Molotov, and detonate 12 molotov grenades

In one game, kill two bosses without killing any other zombie in between

Accumulate 90 seconds of Bullet Time in one single player game

In an On-line coop game, play as the Scout and detonate 5 flash bangs in a single game

In an On-line coop game, play as the Sniper and deliver the killing blow to 10 bosses using the M107 in a single game

In an On-line coop game, play as the Medic and revive team members 15 times in a single game

In an On-line coop game, play as the Gunner and detonate 50 explosives (grenades, dynamite) in a single game

From the start of a game, kill at least one of each zombie boss type while not dropping your health below 100%

Kill two Minigun zombie bosses within two minutes of each other

From the start of a game, survive for 15 minutes without holding or picking up any grenades

Survive for 15 waves on The Farm barricade map

Survive for 30 waves on The Farm barricade map

In a single FreePlay game, survive for 5 minutes without your stats accuracy dropping below 50%

Reach a stats KillStreak of 1000 zombies

Reach a stats KillStreak of 2000 zombies

Reach a stats KillStreak of 3000 zombies

Kill 500,000 zombies