Here is the full list of all 42 Gunpoint achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Voluntarily tell Katie the truth.
Tell Gessler that Rooke's hired you to betray him.
Knock Fritz Gessler out of his office window.
Slam Fritz Gessler's office door into him.
Defeat Gessler by rewiring his gun.
Free an innocent man at the expense of catching a guilty one.
Jump into an Enforcer to knock him through a window.
Mock the chief of police at a critical moment.
Notice the story doesn't necessarily gel with the mechanics. Become qualified games journalist.
This is an achievement in name only. No-one admires you for punching a guy that many times.
Beat Fritz Gessler to death.
Knock Fritz Gessler out with a punch.
Intimidate Fritz Gessler into surrendering.
Chicken out of telling Katie the truth at the last minute.
Use the Prankspasm to knock out someone who isn't standing near a power socket (outside of the test lab).
Complete a mission faster than I can.
Create a custom mission with at least one objective.
Publish your personalised epilogue.
Complete the game.
Kick Fritz Gessler's office door into him.
Help justify my early, not entirely wise choice of game name by holding someone at gunpoint with the Resolver.
Shoot Fritz Gessler.
Catch a guilty man at the expense of freeing an innocent one.
Use the Longshot to make a guard unintentionally shoot another (outside of the test lab).
Use the Hushcracker to jump through a window silently (outside of the test lab).
Use the Gatecrashers to kick a door through a window.
Use the Gatecrashers to kick a door into a guard.
Use the Gatecrashers to kick a door off its hinges.
Upgrade your battery capacity to the non-figurative max.
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
Upgrade your Bullfrog Hypertrousers to pounce instantly.
Complete the police chief's missions without incriminating yourself.
Complete a mission that has guards with no violence, witnesses or loud noises.
Use no violence at all on a mission that has guards.
Conceal your presence at the DataSec break-in from Mayfield.
Steal Gessler's technology for Rooke.
Use the Crosslink to create an infinite loop that burns itself out.
Get knocked down by an opening door.
Knock a guard out by opening a door into him.
Use the Dropshot to land silently from a great height.
Wire an elevator button to trigger something when the elevator arrives.
Leave no living witnesses to your presence on a mission that has guards.