Here is the full list of all 57 Bunch of Heroes achievements.
Kill 200 Strong Martian
While in survival mode and playing alone: get to wave 3 in less than 5 minutes
Eliminate 1,000 Zombie Chickens
Eliminate 723 zombie chickens, 821 basic zombies and 394 zombie astronauts
Complete a mission without dying
Complete a mission without picking up any weapons
Eliminate 200 Martian with shields
Eliminate 500 zombie astronauts
Defeat Fatzi
Complete all cemetery missions
Defeat Jazzy
Complete all farm missions
Defeat Fred
Defeat Pumpking
Eliminate 1,000 Basic Zombies
Survive up to the 20th wave in Santa's map in any difficulty
Reach a combo of 60
Perform a 80 kill combo while in survival mode
Reach a combo of 40
Reach a combo of 20
Complete 1 mission without picking up any Ultra Charges
Reload your extra weapon 1,000 times
Complete all Mars missions
Complete a multiplayer mission without damaging any allies
Eliminate 200 zombies with melee attacks
Eliminate 1,000 Zombie Evaders
Eliminate 100 Martian Teleporters
Eliminate 1,000 Radioactive Zombies
Eliminate 100 Flying-Saucers
Eliminate 200 Martians with melee attacks
Eliminate 1,000 Walking Coffins
Eliminate 1,000 Generals
Complete all missions
Complete a mission with full health
Protect 50 cheerleaders
Burn 1,000 Zombie Chickens
Place 100 turrets
Kill 5.000 Martians
Check out the Credits
Complete a mission with each of the characters
Eliminate 1,000 Zombies with bayonets
Roll 20 times while on fire
Eliminate 200 Zombies with market cars
Complete 10 4-player missions
Perform 100 Ultra Attacks
Pickup 1,000 weapons
Pickup every weapon in the game
Eliminate 35.000 zombies
Kill the Martian King
While in survival mode and playing alone: get to wave 3 without having been damaged
While in survival mode get to wave 12 playing alone
Kill a Martian Teleporter in survival mode
Get over a 1.000.000 points in survival
Get to survival's wave 5 in less than 3 minutes
While playing with 1 ally get to survival's wave 6 without anyone dying
While playing with 2 allies get to survival's wave 9 without anyone dying
While playing with 3 allies get to survival's wave 9 without anyone dying