More like REM World

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Tolkien's legendariumUniverse
universe163 books1923
Set in secondary world.
“Before the seas were bent and the mountains raised, there was Music — and from that Music came Arda, and in the west of Middle-earth the long defeat and stubborn hope of those who dwell there.”
from the catalogue
Start with The Fellowship of the Ring →
includes The Hobbit, The Lord of the Rings, The History of Middle Earth, The Fall of Gondolin, The History of the Lord of the Rings
The Halloween TreeNovel
Ray Bradburystandalone novel1972
About friendship and grief and loss, set in our world.
“Eight boys gather on Halloween night to trick-or-treat with their ninth friend, Pipkin, only Pipkin never shows, having vanished on some errand that may cost him his life.”
from the catalogue
The Wildwood ChroniclesSeries
series3 books2011
Portal fantasy, about friendship.
“Praised for its illustrations and old-fashioned book design, the trilogy continues across Under Wildwood and Wildwood Imperium.”
from the catalogue
Start with Wildwood →
InterWorldSeries
series3 books2007
Portal fantasy and science fiction, set in parallel universe.
“Michael Reaves developed the story with Neil Gaiman, and Reaves's daughter Mallory Reaves co-wrote the two sequels.”
from the catalogue
Start with InterWorld →
Un Lun DunNovel
China Miévillestandalone novel2007
Portal fantasy, about chosen one, set in otherworld.
“The title is derived from 'UnLondon,' the name of the alternate realm where the book is set.”
from the catalogue
SummerlandNovel
Michael Chabonstandalone novel2002
Portal fantasy, set in parallel universe.
“Summerland weaves elements of a World Series, parallel-universe road trip, and a hero's odyssey.”
from the catalogue