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 Longshot to make a guard unintentionally shoot another (outside of the test lab).
Upgrade your Bullfrog Hypertrousers to maximum jump strength.
Steal Gessler's technology for Rooke.
Conceal your presence at the DataSec break-in from Mayfield.
Complete a mission that has guards with no violence, witnesses or loud noises.
Use no violence at all on a mission that has guards.
Use the Dropshot to land silently from a great height.
Get knocked down by an opening door.
Use the Crosslink to create an infinite loop that burns itself out.
Upgrade your Bullfrog Hypertrousers to pounce instantly.
Leave no living witnesses to your presence on a mission that has guards.
Wire an elevator button to trigger something when the elevator arrives.
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 Prankspasm to knock out someone who isn't standing near a power socket (outside of the test lab).
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 off its hinges.
Use the Gatecrashers to kick a door into a guard.
Use the Gatecrashers to kick a door through a window.
This is an achievement in name only. No-one admires you for punching a guy that many times.
Create a custom mission with at least one objective.
Upgrade your battery capacity to the non-figurative max.
Jump into an Enforcer to knock him through a window.
Complete a mission faster than I can.
Complete the game.
Publish your personalised epilogue.
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.
Complete the police chief's missions without incriminating yourself.
Mock the chief of police at a critical moment.
Free an innocent man at the expense of catching a guilty one.
Catch a guilty man at the expense of freeing an innocent one.
Knock Fritz Gessler out with a punch.
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.
Kick Fritz Gessler's office door into him.
Notice the story doesn't necessarily gel with the mechanics. Become qualified games journalist.
Slam Fritz Gessler's office door into him.