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.
Tell Gessler that Rooke's hired you to betray him.
Complete the police chief's missions without incriminating yourself.
Mock the chief of police at a critical moment.
Slam Fritz Gessler's office door into him.
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).
Create a custom mission with at least one objective.
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.
Upgrade your battery capacity to the non-figurative max.
Knock Fritz Gessler out of his office window.
Defeat Gessler by rewiring his gun.
Intimidate Fritz Gessler into surrendering.
Kick Fritz Gessler's office door into him.
Shoot Fritz Gessler.
Beat Fritz Gessler to death.
Complete a mission faster than I can.
Use the Gatecrashers to kick a door through a window.
Use the Hushcracker to jump through a window silently (outside of the test lab).
Publish your personalised epilogue.
Complete the game.
Knock Fritz Gessler out with a punch.
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 into a guard.
Use the Gatecrashers to kick a door off its hinges.
Steal Gessler's technology for Rooke.
Knock a guard out by opening a door into him.
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
Complete a mission that has guards with no violence, witnesses or loud noises.
Conceal your presence at the DataSec break-in from Mayfield.
Upgrade your Bullfrog Hypertrousers to pounce instantly.
Jump into an Enforcer to knock him through a window.
Use no violence at all on a mission that has guards.
Get knocked down by an opening door.
Use the Crosslink to create an infinite loop that burns itself out.
Voluntarily tell Katie the truth.
Use the Dropshot to land silently from a great height.
Wire an elevator button to trigger something when the elevator arrives.
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.