From publisher blurb:
In this simple ebook, you will find conversions to all the mechanics used in the Koryo Hall of Adventures campaign setting book. From the Mudang, Jaein and Sunim classes, to the beasts, and a comprehensive set of tables to generate your own wild spirits, everything is there for you to bring the world of the original book into your OSR game. (This ebook includes only mechanics. If you want to get the full experience with lore, mythology, more races, NPCs, Jeosung’s Gazetteer, and a whole lot more, make sure to get the full Koryo Hall of Adventures in addition to this conversions document).