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