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