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