This book is intended as an aid to writers in creating Compatible Products according to the latest version of the "APOCalypse 2500 Role Playing Game Compatible Products License" available for download on this website. This book will not replace the Main Rule Book or other APOCalypse 2500 core rulebooks which will be needed for reference when converting or designing compatible products. This book will help you grasp the purpose behind basic game fundamentals (game system), nature of the Game Universe, and fantasy concepts from a writer and game designers point of view. This book is also an excellent resource for those wishing to convert other games elements to the APOCalypse 2500 RPG Percentile System. APOCalypse Books are Available World Wide At:    Lulu.com also on Amazon.com / uk /fr / it / de