From the introduction: A rendition of the 1974 "0e" Edition of the World's Most Famous Fantasy Roleplaying Game, with elements borrowed from "original" era RPG gaming and modern d20 theory. Based on The Black Hack and Dying in a Tomb. The Rat Hack is a traditional tabletop roleplaying game hack, played with paper, pencils and dice - it uses the 1970's Original Roleplaying Game as a base. it adds and removes elements to make it a distinct streamlined flavor of the original game.