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.
Slam Fritz Gessler's office door into him.
Complete a mission faster than I can.
Knock Fritz Gessler out of his office window.
Intimidate Fritz Gessler into surrendering.
Kick Fritz Gessler's office door into him.
Defeat Gessler by rewiring his gun.
Beat Fritz Gessler to death.
Shoot Fritz Gessler.
Free an innocent man at the expense of catching a guilty one.
Tell Gessler that Rooke's hired you to betray him.
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).
Upgrade your battery capacity to the non-figurative max.
Jump into an Enforcer to knock him through a window.
This is an achievement in name only. No-one admires you for punching a guy that many times.
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.
Use the Gatecrashers to kick a door through a window.
Use the Gatecrashers to kick a door off its hinges.
Use the Gatecrashers to kick a door into a guard.
Catch a guilty man at the expense of freeing an innocent one.
Use the Longshot to make a guard unintentionally shoot another (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 Bullfrog Hypertrousers to pounce instantly.
Complete the police chief's missions without incriminating yourself.
Steal Gessler's technology for Rooke.
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
Conceal your presence at the DataSec break-in from Mayfield.
Complete a mission that has guards with no violence, witnesses or loud noises.
Knock a guard out by opening a door into him.
Use the Hushcracker to jump through a window silently (outside of the test lab).
Use no violence at all on a mission that has guards.
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.
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.