There are a series of books that were once known and feared for having the all of the knowledge that has ever been learned in human history. These books were long forgotten, but were one day re-discovered by Bowser; you must find the books before he can discover how to use them!
This is a hack that I've been working on for a very long time (you may remember a hack called "Super Mario Planet." This evolved from that). It features graphics that were almost entirely drawn by me (and some Icegoom, naturally), custom music, and many custom blocks. You can find the thread here.
Warning: this hack's music can break in accurate emulators
Here's to hoping you enjoy this demo!
July 9th 2019 edit:
The progress on the newer version of this hack, Aether: The Infinite Library, is available here.