Here is the full list of all 42 Gunpoint achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Use the Prankspasm to knock out someone who isn't standing near a power socket (outside of the test lab).
Beat Fritz Gessler to death.
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.
Knock Fritz Gessler out of his office window.
Defeat Gessler by rewiring his gun.
Intimidate Fritz Gessler into surrendering.
Notice the story doesn't necessarily gel with the mechanics. Become qualified games journalist.
Kick Fritz Gessler's office door into him.
Knock Fritz Gessler out with a punch.
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.
Complete the police chief's missions without incriminating yourself.
Complete a mission that has guards with no violence, witnesses or loud noises.
Complete a mission faster than I can.
Shoot Fritz Gessler.
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).
Use no violence at all on a mission that has guards.
Create a custom mission with at least one objective.
Upgrade your battery capacity to the non-figurative max.
Publish your personalised epilogue.
Complete the game.
Help justify my early, not entirely wise choice of game name by holding someone at gunpoint with the Resolver.
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.
Use the Crosslink to create an infinite loop that burns itself out.
Jump into an Enforcer to knock him through a window.
Upgrade your Bullfrog Hypertrousers to pounce instantly.
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
Steal Gessler's technology for Rooke.
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 the Dropshot to land silently from a great height.
Wire an elevator button to trigger something when the elevator arrives.
Get knocked down by an opening door.
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.