Here is the full list of all 50 Citizens of Earth achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Get all citizens to Lv 30.
Earn $100,000 in the Casino.
Use 150 items.
Enroll 9 citizens simultaneously in School.
Ambush 10 enemies in a row.
Recruit all 40 citizens.
Defeat the Alien Commander.
Defeat the Secretary Supreme.
Defeat the Mishmasher.
Defeat Colonel Cookie.
Defeat the Hippie Guru.
Defeat Honcho Villa.
Defeat DJ Voodoo.
Complete all Extermination quests.
Use 75 items.
Complete all Wanted Poster quests.
Complete all Photography quests.
Recruit 25 citizens.
Defeat Agent D.O.O.M.
Defeat 1,000 enemies.
Receive 10,000 damage in combat.
Collect 300 items.
Find 100 treasures.
Use 25 items.
Spend $10,000.
Defeat the Puppet President.
Earn $10,000.
Spend $3,000.
Defeat 250 enemies.
Collect 100 items.
Get one citizen to Lv 20.
Find 45 treasures.
Deal 10,000 damage in combat.
Get one citizen to Talent Lv 3.
Receive 2,500 damage in combat.
Discover 30 locations.
Earn $3,000.
Discover 20 locations.
Spend $1,000.
Defeat Mr. Mocha.
Collect 30 items.
Deal 2,500 damage in combat.
Find 15 treasures.
Receive 500 damage in combat.
Defeat 50 enemies.
Earn $1,000.
Deal 500 damage in combat.
Recruit 5 citizens.
Discover 10 locations.
Defeat the Opposition Leader.