I have begun compiling a list of online texts that attempt bringing to a complete form the stories the Professor left unfinished: not mere fanfiction, but reasoned works that try to stay in the spirit of what Tolkien would have done if he stayed on the topic.

"Lost Tales": Gilfanon's Tale - https://redlib.catsarch.com/r/tolkienfans/comments/1uwrt3v/finishing_the_lost_tales_a_harmonised_version_of/

"Lost Tales": Eärendel - https://redlib.catsarch.com/r/tolkienfans/comments/1v0u8nq/finishing_the_lost_tales_the_lost_tale_of_e%C3%A4rendel/

"Lost Tales": Prologue and End - https://redlib.catsarch.com/r/tolkienfans/comments/1v7qppi/finishing_the_lost_tales_the_end_of_the_tales_and/

"Lost Tales" (general): https://lotrfanon.fandom.com/wiki/The_Book_of_Lost_Tales,_Remade

The Lost Road - https://lotrfanon.fandom.com/wiki/The_Lost_Road

Does anyone know other ones?