Here is the full list of all 25 Corpse Mob achievements.
Kill 500 zombies with the Axe
Kill 500 zombies with the Baseball Bat
Kill 500 zombies with the Chainsaw
Kill 500 zombies with the Golf Club
Kill 500 zombies with the Katana
Kill 2500 zombies with the Pistol
Kill 2500 zombies with the Bazooka
Kill 2500 zombies with the Machine Gun
Kill 2500 zombies with the Railgun
Kill 2500 zombies with the Shotgun
Kill 100 Queens
Blow up 50 Nukes
Play a co-op game
Unlock Custom Game mode
Complete all waves in a custom game
Reach level 10 with a player profile
Reach level 20 with a player profile
Reach level 30 with a player profile
Reach level 40 with a player profile
Complete wave 15 in Battle mode
Kill Brutus
Kill Megastinker
Kill the Splitter
Kill the Stalkers
Kill the SuperQueen