ERB. Writers create a new kind of place at an sf/f interface.
In Anderson's "The Saturn Game," a group of characters in a hard sf setting like totally immerse themselves in a fantasy role playing game although we see only their physical environment and not also their imagined realm. In Anderson's "The Queen of Air and Darkness," telepathic aliens in a hard sf setting simulate a fantasy world and, in this case, we do see some of what the enchanted kidnapped human children perceive. They converse with fairies which are a "glamour" of reptiloids.
In SM Stirling's Emberverse, the loss of technology enables some gamers to reenact, e.g., medievalism and Tolkienism. But something else is happening. Is a hard sf setting becoming a fantasy setting where Powers can intervene in human affairs? Or maybe it is not becoming? There never was an explanation for the white light of the Change so maybe it was magical/mystical/mysterious/supernatural/divine/demonic from the beginning?
Only time and further reading will tell.