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