Here is the full list of all 42 Gunpoint achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Mock the chief of police at a critical moment.
Free an innocent man at the expense of catching a guilty one.
Slam Fritz Gessler's office door into him.
Defeat Gessler by rewiring his gun.
Kick Fritz Gessler's office door into him.
Shoot Fritz Gessler.
Knock Fritz Gessler out of his office window.
Intimidate Fritz Gessler into surrendering.
Tell Gessler that Rooke's hired you to betray him.
Chicken out of telling Katie the truth at the last minute.
Voluntarily tell Katie the truth.
Complete the police chief's missions without incriminating yourself.
Complete a mission faster than I can.
Jump into an Enforcer to knock him through a window.
Create a custom mission with at least one objective.
Use the Longshot to make a guard unintentionally shoot another (outside of the test lab).
Use the Prankspasm to knock out someone who isn't standing near a power socket (outside of the test lab).
Upgrade your Bullfrog Hypertrousers to pounce instantly.
Publish your personalised epilogue.
Notice the story doesn't necessarily gel with the mechanics. Become qualified games journalist.
Complete the game.
Beat Fritz Gessler to death.
Knock Fritz Gessler out with a punch.
Catch a guilty man at the expense of freeing an innocent one.
Use the Gatecrashers to kick a door through a window.
Use the Gatecrashers to kick a door off its hinges.
Use the Gatecrashers to kick a door into a guard.
Upgrade your battery capacity to the non-figurative max.
Conceal your presence at the DataSec break-in from Mayfield.
Help justify my early, not entirely wise choice of game name by holding someone at gunpoint with the Resolver.
Steal Gessler's technology for Rooke.
Knock a guard out by opening a door into him.
Wire an elevator button to trigger something when the elevator arrives.
Use the Hushcracker to jump through a window silently (outside of the test lab).
Get knocked down by an opening door.
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
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 Crosslink to create an infinite loop that burns itself out.
Use the Dropshot to land silently from a great height.
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.