Cheat Mode:
When you complete the game under the Extreme difficulty setting the options for God mode, infinite ammo and to spawn any weapon will become unlocked.
Achievements:
Easy "Cheers!" achievement:
Enter the "Options" menu, select "Gameplay", then set the
"Are You Drunk?" option to "Yes".
Easy "Mainstream Guy" achievement:
Hipsters can be found in the "Downtown" level at the coffee
shops and phone stores.
Easy "Postal Dude Would Be Proud" achievement:
Play the "Downtown" level to start with a flamethrower and
three Molotov cocktails on the ground in front of you. Target
the crowd of people that is also in front of you.
Easy "Winners Don't Use Drugs" achievement:
Execute twenty of the people found lying on mattresses in the sewer.
Easy "The Witcher" achievement:
Press [Space] to roll and dodge. Perform this action 200 times.