From the introduction:
Hello and welcome to Nightmare Worlds: Corebook, the first book in the Nightmare Worlds line of role playing games. Written with the love of horror and the grotesque in mind, this book contains everything you need to host your own horror table top rpg using the Nightmare Worlds system. We cover the basics naturally, from rules of play, to character creation, and most anything else you’d come to expect from a role playing game. We also give tips on adventure and campaign construction, along with ideas for settings and creature design.
Nightmare Worlds was written to accomplish three goals for the author
that, more or less, revolve around sake of ease. First, this book was designed to be a stand alone product. That means that while we’d love to have you buy every book in the line, we do not cripple your game by requiring you to buy a dozen different books to get a complete usable system. The author is a budget gamer like many others, and we’ve included everything you need here, from character creation to tips on adventure construction and setting. The second goal was to make the system very simple to use. Playing Nightmare Worlds is as easy as flipping a playing card, as our entire system uses a simple playing card mechanic. A deck of playing cards, some paper and pens, and a few friends is all you need. There is some prep work in ensuring your playing the right cards (see below), but for the most part it is very minor. Finally it should be stated that Nightmare Worlds was designed to be a "generic" system for the most part, meaning that it is meant to be a tool for Game Masters first and foremost for use in anything they wish to design. This means that there isn’t some constrained setting that ties deeply into the rules system. While we’ll be providing some backdrops for you to use in the form of campaign setting books, we won’t hamstring your designs and ideas for your game. Anyway, thanks again for your purchase of Nightmare Worlds: Corebook, I hope you have a good time!