Here is the full list of all 24 Zombie Camp: Last Survivor achievements.
Died 25 times
Killed 10000 zombies
Killed 5000 zombies
Killed 100 zombies with the shotgun
Killed 100 zombies with the thumper
Killed 100 zombies with the sniper rifle
Fully upgraded the sniper rifle
Fully upgraded all weapons
Fully upgraded the Thumper
Unlocked the sniper rifle
Reached level 16
Fully upgraded the shotgun
Killed 200 zombies with the gatling gun
Unlocked the Thumper
Killed 100 enemies with the gatling gun
Fully upgraded the AK47
Killed 1000 zombies
Achieved 500 head-shots
Unlocked the Shotgun
Fully upgraded the pistol
Unlocked the zombie farm (Level 5 unlock)
Unlocked the AK47
Killed 100 zombies with the pistol
Killed the Skeleton King