tagged with Lovecraftian Horror and Sexual Content. Score should reflect how important it is for the story (I'd ignore anything below Saya no Uta), Rating is how much people liked it. Click on Sexual Content and select "invert" if you're fine with non-erotic ones.
As far as Lovecraftian goes, you can get much more Lovecraftian than Lust for Darkness and its sequel Lust From Beyond. The Whole premise of these two is their similarity to the worldscapes of Lovecrafts design. It evokes the feel so well that it's almost like Lovecraft returned from the dead, a now extreme sexual deviant, and made the game himself