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