From the back cover: The Player's Companion is the first expansion for the Adventurer Conqueror King System (ACKS) and an invaluable resource for players and Judges of the original fantasy role-playing game and its retro-clones. The Player's Companion allows you to customize your fantasy game to an unparalleled degree. Open up the hood of the Adventurer Conqueror King System and gain new insights into the foundations of the original fantasy RPG!