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