Here is the full list of all 21 Humans Must Answer achievements.
Collect 50% of the golden eggs
Defeat The Martian Drill Laser
Upgrade any weapon to max level
Defeat DNA
Collect 25% of the golden eggs
Obtain the support weapon
Defeat Sheriff Gilgamesh
Beat 1 level to 100% (Gold status)
Collect 10% of the golden eggs
Pass border patrol
Take the Chicken's Way Out
Kill The Starbound Penguin
Collect 75% of the golden eggs
Collect 100% of the golden eggs
Defeat The Ankh
Beat 5 levels to 100% (Gold status)
Beat 10 levels to 100% (Gold status)
Beat 15 levels to 100% (Gold status)
Beat 20 levels to 100% (Gold status)
Die as a hero, live as a villain
When you do things right, people won't be sure you've done anything at all