The Islands of Purple-Haunted Putrescence is an adventure and campaign guide intended to be compatible with virtually any game based on old school versions of Dungeons & Dragons. The setting is inspired by weird fantasy, and the book has a number of variant rules including a number of mechanics designed to give the players more narrative control, tools for building character backgrounds, alterations to the standard spellcasting system, and the monk character class. There is some background detail on the Purple Islands themselves (including the eponymous being), and the adventure mixes fantasy, science fiction, Lovecraftian threats, and women in distress.

Has a "Caution: mature content!" warning for nudity and adult themes.