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