Follow the Cthulhu-style "tragic victory" and "open ending". The main threat (the arrival of Hastur) was temporarily prevented, and the core of the cult was destroyed, but at a huge cost (the protagonist was alienated and disappeared, important supporting characters died, and the world was permanently polluted). The threat has not been eradicated (the debris remains, the pollution continues, the ancient gods are still watching), and the survivors continue their small but tenacious struggle in a scarred world. The final state of the protagonist Keles is tragic. He became part of the fight against darkness, but lost himself.
