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