Yes, that title does have a familiar ring to it, doesn't it? Gary Gygax didn't include the 1908 novel by British author William Hope Hodgson in Appendix N, but I've always wondered whether he might have read the book, which was a favorite of H.P. Lovecraft. Regardless, The House on the Borderland is an important work, having one foot planted firmly in the established 19th century genres of the ghost story and the Gothic novel and another planted in the nascent genre of cosmic horror. Despite this, it's comparatively little known or discussed.
The novel is the tale of two friends traveling in rural Ireland, who discover the ruins of a strange house in the middle of a large chasm. Inside the house, the friends find the journal of the man who lived here and they take it and read it. The journal explains that the man lived here with his sister and pet dog before experiencing many terrible visions of demons and pig like "swine-things" (as he calls them). Not long thereafter, he discovers a pit near his home, which he finds fascinating and attempts to explore. Within the pit dwell the very swine-things he saw in his vision. He attacks and slays several of them and seemingly drives them away. Unfortunately, the strange creatures are not the only thing that's gone awry. Time itself seems to be behaving strangely, with day and night moving at different speeds until, at last, the world seems to be enveloped in eternal dusk. From there, the journal describes even stranger events, resulting in a climax I will not spoil here.
The House on the Borderland is, like many early 20th century novels, difficult to read at times, both because of its language and because of its style. Nevertheless, I can fully understand why Lovecraft liked it so much (though he did charge Hodgson with "a tendency toward conventionally sentimental conceptions of the universe, and of man's relation to it and to his fellows" in Supernatural Horror in Literature). This is a novel that goes beyond the traditional horrors found in the Gothic tradition and attempts something more outré and phantasmagoric. It plays with notions of rationality and sanity and the malleable nature of reality. It's definitely not as bleak a vision as that of Lovecraft but you can certainly see the beginnings of HPL's brand of horror within it.
In gaming terms, I've long found the book quite inspirational. A strange, isolated location where reality bends and warps according to other laws is an attractive idea and many an adventure has borrowed it. My recent work on The Cursed Chateau certainly has a bit of Hodgson lurking within it and I doubt I'm alone in having stolen an idea or two from the book. Though first published in 1908, it achieved wider fame in its 1948 appearance in an Arkham House collection named after it and whose cover I've posted along with this entry. I imagine it's in this edition that quite a few future game designers would have encountered Hodgson's novel for the first time.