Since the game is on the Source engine, there is a developer console here.
Postal 3: Cheat Codes Free Download
To activate it you need:
Go to Settings / management / advanced / check the “ developer console ”
List of working codes:
Sv_cheats 1 – activates cheats mode
god 1 – Immortality
notarget 1 – invisibility
Cheat Codes work and after turning them off, to turn them off, enter this code again. Good luck to you!