Manual of the Planes - The Forgotten Lore Universe

From the introduction: This specific compilation of rules, house rules, and errata details the particular Universe that is an on-going project of Michael Jones and Phil Knopp. It is based on the traditional 1st edition AD&D rule books and other core material but has been customized and elaborated upon over the years to become tailored to their gaming preferences, style, and personal tastes. We have chosen to call it the “Forgotten Lore” Universe.