Here is the full list of all 35 Postal III achievements.
Kill 1000 unarmed bystanders.
Kill/incapacitate 235 terrorists.
150 kills using fire.
50 kills using bees.
50 kills using cat.
Euthanise 30 elderly folks.
Respawn 20 times.
Spend 900 seconds or more in catnip bullet time.
Piss 100 gallons of urine.
Suck up 500 items with the shop vac.
50 kills using boomerang machete.
Smash 50 windows.
100 kills using machete in melee.
Taze 200 victims.
Choose path for the first time.
Take out all the criminal scum infesting Catharsis!
Make Venezuela peacemakers go home.
Arrest eco zealots leader.
Arrest 200 perps.
50 badgersaw kills.
Destroy 50 cars.
Beat game with zero kills.n(zombies and bosses don't count)
Escape from prison.
300 headshot/decap kills.
Finish your business with Krotchy.
Kill no animals in one playthrough.
Complete game using only melee.
Complete game using only the pistol.
Complete Good path without falling off.
Complete game killing only males.
Beat the game once. No restrictions apply. Everyone's a winner.
Return Thegways to the owner
Injure yourself.
200 kills using M-60.
Disobey orders, given to you, and see what happens.