Running With Scissors' Postal series is well known for being controversial, primarily because of how violent the first two games are. However, Postal III caused problems for an entirely different reason, solidifying it as the worst in the series' history.
When work on Postal III started, Running With Scissors was in need of help and called in the aid of a Russian studio named Akella, which had aided development of Postal II. The team at Akella was also much bigger and better funded at the time. Unfortunately, Akella fumbled through development, with setback after setback. What Akella ended up releasing was so bad, the folks at Running with Scissors refuse to sell or acknowledge it, stating that the final product was nothing like the studio expected.
YouTuber Matt McMuscles explains that part of the problem with Postal III's development can be blamed on the 2008 financial crisis, which hit Akella hard. The company had layoffs and the team working on the game was fired. This pattern happened several times, until only one team with very few people remained. McMuscles notes that at this point, Running with Scissors begged Akella to just mercy kill the whole thing, but Akella was determined to release Postal III to recoup at least some costs.
Postal III is a buggy mess. As youtuber Civvie11 shows in his comprehensive review of the game, playing is difficult when things don't function correctly. Attacks connect incorrectly or simply fail to connect at all when kicking or fighting bare handed. Guns sometimes fail to produce a headshot even if the enemy is hit there. The game also crashes frequently, at random times.
Perhaps one of the biggest broken features is the game's Karma Meter, which tells a player how good or evil they're being based on in-game actions, represented by a smiley face. When players kill innocents or start fights with cops, the face slowly turns into an evil red face, locking the player on a bad path. The meter is supposed to be able to gain yellow back, but it's broken in Postal III and doesn't actually do that. Players who follow the bad ending get a disappointing surprise.
This is a Postal game where the bad actions get are punished within the story and the real ending gets locked behind the good ending. A message tells players that if they want the ending where they get to kill the three bad guys themselves, they need to go play the good path instead.
The game's story and humor doesn't exactly do it any favors, either. The Postal Dude is in the town of Catharsis, where all sorts of misadventures befall him. Where the second game is darkly humorous or vile, Postal III moves for bad meta jokes or plain odd humor. The Dude makes meta commentary on what's happening and the names of characters like Police Chief Lt. Deutschbagge don't help.
When players go to the Running With Scissors website, the link for Postal III leads directly to a Rick Roll. The studio was so ashamed of the game that it prompted an apology and add-on content for Postal 2, Paradise Lost. This rewrote the series so the third game was a fever dream that never happened.
Postal III is a great example of Murphy's Law in action. Everything that could go wrong for this game did, and the final product exemplifies this. The game is a broken mess full of cringey meta humor, crashes and a horrifying development process. It's a product so bad, the Running With Scissors won't even sell it. It's very obviously the worst in the series.