Here is the full list of all 23 Featherpunk Prime achievements.
Kill first sentinel.
Completed First floor.
Completed the tutorial.
Take down Guardian 1.
Take down Guardian 2.
Take down Guardian 3.
Take down Guardian 4 and destroy Cybirdroid.
Activate the checkpoint.
Destroyed 10 times.
All Sector 1 collectibles collected.
All Sector 2 collectibles collected.
All Sector 3 collectibles collected.
All Sector 4 collectibles collected.
Every collectible in every sector collected.
Complete the Boss 1 without dying.
Kill 500 enemies.
A funky hat for F-Droid.
Kill 100 enemies during Overdrive.
Less than 10 health pickups used.
Complete the game with killing all Guardians the first time.