Just had a thought for a CoC game. Whatever horrible insane cultists are trying to summon some kind of great old one or outer god or what-have-you, or whatever abominable creature(s) have broken through and are wreaking havoc, are so far along that the investigators can't possibly disrupt the ritual or fend off the critters or otherwise solve the problem by conventional means. The only option would be to find a way to consult Yog-Sothoth itself for some ritual that would stop it, without going too insane in the process to do what's necessary once they gain the requisite knowledge. Instead of investigating the cults and the monsters, the goal would be to find ways to contact the Lurker at the Threshold, 'Umr-at-Tawil, the All-in-One and One-in-All without being obliterated, driven mad, or ascending beyond the concerns of petty mortals to such a degree they no longer care about earth and trivial things like an insignificant blue planet in an outer spiral arm of a backwater galaxy getting conquered by Hastur. In essence fighting fire with fire, becoming cultists themselves to fight the other cultists.