Main world is library, which is a location in the real world. The library was originally written in a book, though, and that book has been torn apart by a book-dweller seeking power. The deeper areas of the library are increasingly corrupted and damaged.
Dungeon areas are books within the library, accessed via linking. Monsters have spilled out of them. The deeper you go into the library, the harder the dungeons become.
Each dungeon contains 1 or more pages of the Book of the Library (Illúmbelía). Your goal is to retrieve as many pages as you can (at least a certain % of the book), recover the quill (from the final boss), find the book’s remains, and repair it. More pages beyond the threshold = more final score.
Food timer may run at different speeds in damaged books which have time issues.
There is guaranteed to be at least one book that your god does not want you in, whatever your god is.