Here is the full list of all 35 Postal III achievements.
Kill 1000 unarmed bystanders.
Spend 900 seconds or more in catnip bullet time.
50 kills using cat.
50 kills using bees.
150 kills using fire.
50 kills using boomerang machete.
Kill/incapacitate 235 terrorists.
50 badgersaw kills.
100 kills using machete in melee.
Destroy 50 cars.
Euthanise 30 elderly folks.
Make Venezuela peacemakers go home.
Take out all the criminal scum infesting Catharsis!
Arrest eco zealots leader.
Arrest 200 perps.
Taze 200 victims.
Beat game with zero kills.n(zombies and bosses don't count)
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.
Respawn 20 times.
Suck up 500 items with the shop vac.
Piss 100 gallons of urine.
Smash 50 windows.
Beat the game once. No restrictions apply. Everyone's a winner.
Finish your business with Krotchy.
Injure yourself.
Escape from prison.
300 headshot/decap kills.
200 kills using M-60.
Return Thegways to the owner
Choose path for the first time.
Disobey orders, given to you, and see what happens.