More like Castle Perilous

anchored on:fantasyportal fantasytransported to another worldsecondary worldadventurouswhimsical

but

Narrow

Tolkien's legendariumUniverse
universe163 books1923
Fantasy, 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
NarniaUniverse
universe38 books1950
“Once there is a wardrobe at the back of a spare room, and behind the fur coats the wood gives way to snow, and a lamp-post burns alone among the trees.”
from the catalogue
Start with The Lion, the Witch and the Wardrobe →
includes Narnia, Narnia Solo Adventures
The Ship of IshtarNovel
A. Merrittstandalone novel1926
Mythic fantasy, about gods.
“When he finally manages to crack open the rock, a mist escapes.”
from the catalogue
SpellsingerSeries
series9 books1983
About music.
“Alan Dean Foster's Spellsinger series follows Jon-Tom, a UCLA law student pulled into a fantasy world by the wizard Clothahump, where he discovers he can cast spells by singing along with his guitar.”
from the catalogue
Start with Spellsinger →
Quag KeepSeries
series2 books1978
completed
Fantasy and portal fantasy, adventurous in tone, about transported to another world and quests, set in secondary world.
“Andre Norton's Quag Keep holds a notable place in gaming history as the first novel set in Gary Gygax's World of Greyhawk, written after Norton took part in an actual Dungeons & Dragons session with Gygax himself.”
from the catalogue
Start with Quag Keep →
The Barbed CoilNovel
J. V. Jonesstandalone novel1997
Romantasy.