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