Here is the full list of all 31 Zombie Kill of the Week - there are Reborn achievements.
Survive 4 minutes in Night At The Mall. (Challenge mode)
Survive 4 minutes in RedSnow. (Challenge mode)
Get yourself killed with a grenade. Dumbass.
Get the GiGaGirlGannon, and kill 10 zombies within 10 seconds.
Slaughter 5000 zombies in total.
Encounter all 3 tanks, and get them killed.
Open all areas in a single match.
Own atleast 5000$ in one match
Grill 50 zombies with flame in a single match.
Help your friend in need.
You have played ZKW for an hour.
Fight your way to round 20.
Kill the zombie bear before he takes your money.
Stand still for 30 seconds, wondering about your life.
Survive 4 minutes in Abandoned Hospital. (Challenge mode)
Get promoted to rank 10.
Slice 53 zombies in one match.
Get 100 headshots in one match.
Zombies are not ment to fly.
Get 5 meats in a single game from the fridge.
Kill 15 zombies with a katana, and 25 with saw in one match.
Get promoted to rank 30.
You have wasted 5 hours of your life.
And still going?
Go see your friends!
Slaughter 10 000 zombies in total.
Get a shotgun, and make 20 zombies crawl in front of you.
Find the fridge and make it disappear. Repeat 3 times.
Survive 4 minutes in Arise. (Challenge mode)
Survive 4 minutes in Area 73. (Challenge mode)
Survive 4 minutes in Homerun. (Challenge mode)