In some Christian faiths, purgatory is an afterlife realm that awaits anyone who was not, in life, holy enough to ascend straight to heaven or profane enough to go straight to eternal damnation—almost everyone, in fact. Upon death, these people suffer through a period of cleansing trials until they are ready to move on to heaven, a process that might ake years or even centuries. To the modern eye, the recursion known as Purgatory might be indistinguishable from a vision of Hell. It’s a seemingly endless maze of rocky tunnels and large caverns in which sinners stew in fire and water, and torture chambers where punishments ironically suited to specific sins are carried out. Of course, despite appearances, no one in Purgatory is actually a human soul from Earth. All entities, both demonic and those undergoing trials, are born of the same fiction that seeded the recursion itself.
Unlike recursions based in more modern fiction, Purgatory has been around for six centuries. The PCs aren't necessarily the first recursors to explore it, and those who have been there before might have their own agendas. In particular, the Karum have known about Purgatory for some time, and the organization became aware of Dragenesti's gate shortly after it was used. Six hundred years is a long time on Earth, but the Karum haven't forgotten. A Karum leader named Vilet-sha hopes to find the gate and make use of it, but the Quiet Cabal have gotten wind of the plot and are also seeking the gate. The PCs might tangle with Vilet-sha's agents if or when they venture into Purgatory looking for the keys to sealing the gate.