Sidney Sime and Call of Kafka
BTW that's Don Kenn on the header, who's also brilliant. The combination of the two kinda bridges the gap between Edward Gorey and Aubrey Beardsley in my mind's eye.
Elsewhere Zak Smith said: lovecraft in his home era, when the urge to be purist is most intense, is profoundly antisocial and timeless and devoid of cultural markers. It's about people alone in featureless rooms with the landscape... It's like his language strips away so many signifiers of everyday life that it's at its best when dealing with only "eternal" things: a house, a desert, a field, a forest, a museum, an office. Nothing that has any chance of being dated.
Which I think of as "Call of Kafka" or, where the monsters really are up to something conspiratorial and it is society-must-be-defended, then Kafka of Cthulhu.
I would add another strand: for me, the mystery's the thing, but not really in the sense that now you have a puzzle to solve. CoC adventures where you actually do learn something about the True Nature of the Universe strike me as deeply problematic, partly because the monsters turn out to have human-readable motivations after all (what with being created by humans and all). I think my favourite resolution to a CoC mystery might be that you realise at the end of it that now you know less about the Mythos than you did before.
It's hard to make a lot of plots around the concept of the uncaring universe that reveal more about that idea. Like, first there's Roadside Picnic, and you can run across the aliens doing something awful and maybe you have to step into the mincing machine to turn it off, so the question is who's going to do that. And then there could be x-com: which bits of the brain melting machine are we going to try to use to barricade our little planet and keep it safe for humanity, and how hopeless is that as a goal? But then I kinda run out of ideas.
So I think the thing that keeps me loving CoC is that the mystery stays unresolved: you don't know what's going on, and a lot of the plots are really human (because it's stupid humans trying to please the alien masters but they don't know what they want actually and meanwhile ooh look shiny virgins!) and what's behind them is unfathomable which means we're not now going to fathom it around this table in the context of a game.