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