That last bit sounded a bit like Planescape to me, but this next quote, also on page 5, sounds more like something from Spelljammer:Conan: The Roleplaying Game, page 5 wrote:...The demons of the Outer Dark, called up by sorcery or trapped on Earth by bad luck can be quite another matter.
I looked in the Index, at the back of the book, but it does not include The Outer Dark, so I had a skim through and found a Cosmology sction on page 293:Conan: The Roleplaying Game, page 5 wrote:The sorcerers speak of other realms beyond the Earth of the Hyborian Age. The Outer Dark, home to demons; hell itself, home to more diabolic creatures and to lost souls. Beyond the Outer Dark are more planets, often cold and accursed, the source of many a weird monster travelling through the void under its own power or blown as spores by cosmic forces.
Off I went to page 289:Conan: The Roleplaying Game, page 293 wrote:Cosmology
There are other planets than the Earth of the Hyborians. The planet Earth is surrounded by a belt of light, but beyond that is the Outer Dark, home to many a strange demon.
Beyond the Outer Dark, deep within the emptiness of the void. lie several strange planets. The most notable one, which seems to have the closest connection to the Earth, is Yag. It is described variously as a green planet and an accursed planet; presumably because it is covered with weird plant life that is inimically hostile to the life of Earth. At some point thousands of years ago, a great civil war shook Yak, which is when the god Yogath (see p. 289) first came to Earth as an exile. More recently the seeds of the vampiric plant Yothga drifted down to Earth, though they could grow nowhere, but in Hell. Some scholars speculate that Yothga was sent in search of Yogah by the kings of Yag, but it seems equally likely that this cosmic plant reproduces by casting its seeds far into the void.
More information about Yag and the creatures from it can be found in the mysterious tome known as the Book of Skelos.
I did a Google search for the Book of Skelos. It seems to be an in-character book, rather than an out-of-character book, that Mongoose published. But it does also look like Modiphius have used that name for one of their books.Conan: The Roleplaying Game, page 289 wrote:Yogah: Yogah is the strange, elephant-headed star-being from the story The Tower of the Elephant. His memory is worshipped still as a god in Khitai. Probably he is a god of magic and sorcerous knowledge.
Does anyone know if Robert E. Howard wrote more details on how the Outer Dark, the void, Yag and the other planets work? Have any of the various publishers done anything with this space stuff?