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