From the introduction:
FANTASTIC MEDIEVAL CAMPAIGNS is a new version of the ruleset for fantasy wargaming campaigns, first published in 1974. As such, this compiler does not feel compelled to tell you that this book is at all complete, since it is theoretically and practically not so. The variety of readings of the original text emerge from a variety of perspectives—from historical wargamers to science-fantasy enthusiasts to casual players—and the tension between these conflicting interpretations of the text gave rise to the role-playing game hobby as it exists today.
This book contains suggestions and guidelines for how to design and run your own fantasy campaign. In keeping with the spirit of the originals, you may use, ignore, or modify as many of the rules given here as you desire, whether due to your own personal preference, to meet the needs of players as the campaign develops and progresses, or mere whim. Feel free to make such changes in the margins of this book itself. It’s your book. It’s not limited edition or anything.