Stygian Library (Hardback + PDF)

The Stygian Library is a procedurally-generated library dungeon set in the extra-dimensional space between every library in the universe. Each expedition generates its route as it explores, resulting in new locations and forbidden knowledge being discovered with every visit. Included within:

• Systems for generating locations within the library, including Entrance Foyers, Map Galleries, Tea Rooms, Planetariums, Calculation Engines, Phantom Databanks, Paper Beehives, Phantom Pumps, Jarred Brains and the Sheol Computer.
• 40 monsters tailored to the Library, including Lantern Bearers, Skeleton Crew, Origami Golems, Guardian Shades, Lost Souls, Ink Elementals, Animate Spells, Archivist-Liches, Infernal Merchants, Escaped Fictions, Educated Rodents, Conceptual Wells and the orders of Librarians themselves.
• A system for searching for specific knowledge within the library's depths, as well as 30 unusual books and the secret knowledge they contain.
• Tables for generating treasure, dreams, rumors, and various other useful details.
• A unique class of Mummified Sages, post-human academics who've dwelled in the Library for decades or more.

It's a big spooky library full of dangerous knowledge, spiritual automata and ghost-fueled computers.

The adventure includes stats and sparse amounts of mechanics intended to be broadly compatible with most old-school RPG systems, and easily adapted to any other fantasy RPG.