Full list of all 34 POSTAL: Brain Damaged achievements. It takes around 10-12 hours to unlock all of the achievements in the base game on Windows.
The base game contains 26 achievements, and there is 1 DLC pack containing 8 achievements.
Find all codex entries in the These Sunny Daze DLC
Finish the These Sunny Daze DLC
Obtain all These Sunny Daze DLC weapons
Find all secrets on the Sun of the Beach map
Find all secrets on the Ship Happens map
Find all secrets on the E*ection Day