From publisher blurb:
This is an analysis of 5th edition D&D’s underlying mathematics and system for referees to create new races and feats for their campaign settings. There are 37 new races in short form including minotaurs, centaurs, and pixies. This book benefits from three years of playtesting and development. Hundreds of hours of mathematical analysis of evidence from the Players’ Handbook, Dungeon Masters’ Guide, Elemental Evil Player’s Companion, Volo’s Guide to Monsters, and the Tortle Package has determined how canon races are built enabling you to build quality new races for your players. There is also an optional section that contains rules that are NOT part of the reversed engineered system. Rules from the PHB and DMG are applied in new ways to open up a greater diversity of PC races.