I’m imagining Cthulhu cultists finding ancient alien ruins that eventually leads them to a long dead world orbiting a brown dwarf. A dark, foreboding and ancient world, probably a rogue planet flung from it’s home system that fell into orbit around a failed star.
The Mi-Go, ancient servants to an far older beings. Cthulhu and the other old ones, immortal gene-modded so heavily their original forms are indiscernible, evolutionary heritage long abandoned. Ancient advanced technologies, that might as well be near magical to 2300’s investigators.