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