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