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.
Mock the chief of police at a critical moment.
Defeat Gessler by rewiring his gun.
Notice the story doesn't necessarily gel with the mechanics. Become qualified games journalist.
Knock a guard out by opening a door into him.
Slam Fritz Gessler's office door into him.
Kick Fritz Gessler's office door into him.
Beat Fritz Gessler to death.
Knock Fritz Gessler out with a punch.
Knock Fritz Gessler out of his office window.
Intimidate Fritz Gessler into surrendering.
Complete the police chief's missions without incriminating yourself.
Complete a mission that has guards with no violence, witnesses or loud noises.
Conceal your presence at the DataSec break-in from Mayfield.
Complete a mission faster than I can.
Tell Gessler that Rooke's hired you to betray him.
Chicken out of telling Katie the truth at the last minute.
Use no violence at all on a mission that has guards.
Voluntarily tell Katie the truth.
Publish your personalised epilogue.
Upgrade your battery capacity to the non-figurative max.
Create a custom mission with at least one objective.
Complete the game.
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 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.
Steal Gessler's technology for Rooke.
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.
Upgrade your Bullfrog Hypertrousers to pounce instantly.
Jump into an Enforcer to knock him through a window.
Use the Prankspasm to knock out someone who isn't standing near a power socket (outside of the test lab).
Use the Hushcracker to jump through a window silently (outside of the test lab).
Use the Dropshot to land silently from a great height.
Wire an elevator button to trigger something when the elevator arrives.
Use the Crosslink to create an infinite loop that burns itself out.
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.