I've read once an article on the Great Library of Thoth (or Thot or Toth or whatever!) in the Mimir.net website, suggesting the Library is a prison: the entrance is free, but then you don't want to get out, attracted by all the knowledge contained there. It inspired me an adventure hook:
1) PCs are suggested to go to the Library to retrieve one important information for the campaign
2) Once inside they search for this info and additional useful lore, and after when they finally understand they have to leave or die there the exit is disappeared.
3) The only way out: the Tome of Neverending Stories. It's an sentient and powerful book, who want to flee as well as the party. He can pierce the defence of Toth if the PCs are willing to "live" its stories. Or to create new ones. Not totally sure how to develop this....
One solution: they "enter" many old and well known clichè tales (one Gothic legend, one Andersen story, and so on). At the end of all of them (after encountering Dracula, the Little Planescape Mermaid and so on) they must find a hidden "exit" to move to the next story. After entering in the 3-4 exits the find theirselves and the book actually out of the Library. Inside the "tales" maybe there are agent of Toth to stop the PCs. This idea is simple but not so "extravagant" (or better, over abused!)
Otherwise the PCs have the power to create (writing in the Tome) a brand new story where at the end the party manage to get outside the Library (or another prison) and they found them really outside. In this second option the players don't have to play with their characters in the "tales" but they must create a story while the GM try to bend the story towards Toth's side. Have you ever played a card game called "Once upon a time"? Plugin <em></em> Not Found However, this solution seems more appealing but less confusing to me: how can I really play this?
Thanks to everyone for any input!!
If you go with option one (journeying into old stories); you could use the EX1 and 2 Dungeonland models. (And if you go with a suggestion I recently made on a Demiplanes thread, you could write one inspired by the dark elements of Willy Wonka).
If you do use this route, I'd suggest using the stories just as inspiration but pepper them with actualy threats and challenges (Dungeonland may have gone a little TOO far into this direction) as I don't think they would enjoy just acting out a pre-written script of the original story.