Here is the full list of all 42 Gunpoint achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Knock Fritz Gessler out of his office window.
Slam Fritz Gessler's office door into him.
Tell Gessler that Rooke's hired you to betray him.
Conceal your presence at the DataSec break-in from Mayfield.
Create a custom mission with at least one objective.
Jump into an Enforcer to knock him through a window.
Chicken out of telling Katie the truth at the last minute.
Voluntarily tell Katie the truth.
Mock the chief of police at a critical moment.
Use the Prankspasm to knock out someone who isn't standing near a power socket (outside of the test lab).
Intimidate Fritz Gessler into surrendering.
Defeat Gessler by rewiring his gun.
Shoot Fritz Gessler.
Catch a guilty man at the expense of freeing an innocent one.
Complete a mission that has guards with no violence, witnesses or loud noises.
Use the Hushcracker to jump through a window silently (outside of the test lab).
Help justify my early, not entirely wise choice of game name by holding someone at gunpoint with the Resolver.
Upgrade your battery capacity to the non-figurative max.
Notice the story doesn't necessarily gel with the mechanics. Become qualified games journalist.
Get knocked down by an opening door.
Publish your personalised epilogue.
Kick Fritz Gessler's office door into him.
Complete a mission faster than I can.
Complete the game.
Beat Fritz Gessler to death.
Knock Fritz Gessler out with a punch.
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.
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.
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
Steal Gessler's technology for Rooke.
Knock a guard out by opening a door into him.
Upgrade your Bullfrog Hypertrousers to pounce instantly.
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.