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