As often happens, I'll discuss a book in this series that can't, by any reasonable definition, be called "pulp fantasy." Nevertheless, I discuss the book because I think it played a role in the development of the hobby, despite its being very different in style and content from most of the other books that inspired early gamers and game designers. In some case, it's precisely because these books are so different that I include them. They provide a counterweight to the vast majority of what I talk about here, a reminder that the early hobby was in fact a welter of conflicting ideas and approaches, not all of which agreed with one another.
A good case in point is Katherine Kurtz's 1970 novel, Deryni Rising. Set in the imaginary medieval realm of Gwynedd, the novel tells the story of Prince Kelson Haldane as he attempts to claim his rightful throne as king of Gwynedd after the death of his father. Complicating matters is the fact that Kelson is opposed by a powerful sorceress who wishes to claim the throne for herself and whose magical abilities all but guarantee her victory. Kelson's father, the previous king, had held off this pretender through his own magical abilities, which Kelson lacks. The prince must then unravel the mystery of his father's powers in order to succeed him and take his place as Gwynedd's ruler.
Gwynedd is one of the Eleven Kingdoms, a collection of medieval feudal realms, some of which are clear analogs of places in the real world, while others are less obviously so. There are many other analogs to real world institutions, most notably the Holy Church, an inexplicably Christian church, complete with most of the trappings of medieval Catholicism, including ecclesiastical Latin (though there does not seem to be a Pope). Just how and why this fantasy world managed to produce so close a copy of medieval Catholicism is never explained and it's something that never really sat well with me, as the world of the Eleven Kingdoms is clearly not our world or even an alternate version of it. This is made particularly clear by the inclusion of the Deryni, a race of human beings with natural psychic/magical abilities and who are often treated with suspicion, if not hatred, in many of the Eleven Kingdoms.
Deryni Rising is the first of many books set in this world, one that clearly found lots of fans in the early days of gaming. I can't say I'm among them, unfortunately. I have always found them difficult to like, but then I've never enjoyed books that borrow heavily from the real Middle Ages while at the same time changing many elements of the period without any concern for the ramifications. I'm probably in the minority on this score, given the success of George R.R. Martin, whose books seem to be spiritual descendants of Kurtz's (albeit with a great deal more sex and violence). There's little question that the Deryni novels inspired lots of gamers, who took their approach to world design as a model to emulate. These worlds run in parallel to the swords-and-sorcery-inspired worlds that I prefer, but they're no less a part of the heritage of the hobby, even they weren't especially influential on Arneson or Gygax. Still, I can't deny their place at the gaming table and think it worth reading a book or two in the series to get a taste of what they're like and why people fell in love with them.