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