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