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