Dangan Ronpa is already dark, but Doubt Academy takes it even further thanks to a few key differences. Unlike in canon, where convicting the wrong person equals Game Over, here Monobear simply tells them they got it wrong before executing the innocent scapegoat. This creates a Kangaroo Court atmosphere where classmates have already lynched someone they knew was innocent to keep them from taking revenge and others have offered themselves up as Senseless Sacrifices to keep their friends from suffering the same fate.
The Insane Cafe RP trilogy has elements of this. The first was a nonsensical, hilarious and downright Narmy. The second was more plot driven and a terrorist attack on a remote laboratory was a key plot point. The 3rd installment features several assassination attempts, a few sex scenes and an impending war. Oh yeah, profanities are uttered the second and third installments.
While most of the campaigns in the Global Guardians PBEM Universe were standard Bronze Age fare, the Night Life In The Big Easy campaign, which featured a solo 1980s-style vigilante facing off against a voodoo-themed criminal empire that had been built on drugs, prostitution, and white slavery, was straight out of the Dark Age.