Strange Things Without Explanation

Cthulhu, crazy literature, if the protagonist has an IQ and is decisive in doing things, the protagonist is just an unknown person, relying on his own strength to go crazy step by step, carrying a golden finger with him. In a safe world, there are always countless puzzling things. We don't know what he is, or why he is, let alone what he wants to do. Countless victims from different periods have been harmed by him. We don't know what he is, so we give them a general name of "unknown things".