[Phaemorea Rules Supplement is a twenty-]page bookmarked PDF containing suggested rules adaptations for Dungeons & Dragons Rules Cyclopedia. The changes focus on updating classic D&D for the modern audience without sacrificing the very things that made OD&D great. The goal isn't to rewrite an excellent system, but to tweak it with house rules adapted from years of play.
It also offers new rules for Guilds, variant classes and other elements unique to the Phaemorea setting. While the focus is on OD&D, much of the content of this book can be adapted to other settings, such as the important part Thieves' Guilds play in the world.