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