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