From the back cover:
What if Gary Gygax had been allowed to go through with his plans for a second edition of the world's most popular role-playing game?
In 1985, Gary Gygax left TSR, unable to continue development on Advanced Dungeons and Dragons™. However, he wrote several articles in Dragon™ magazine detailing what the new edition of the game would look like, and in later years expanded greatly on those articles in various online forums and other venues. ADVENTURES DARK AND DEEP™ is an attempt to realize those plans and create the game that Gygax was unable to. This detailed tome is the result of years of research and effort, and provides a glimpse into how a new edition of the world's most popular role-playing game might have appeared if its creator had remained at the helm.
This book has over 900 monsters, animals, and other creatures to populate your ADVENTURES DARK AND DEEP™ game (the entries herein are also compatible with most old-school role-playing games). It also includes rules for creating your own monsters or modifying already-existing creatures, the deadly psychic strike attack, rules for humanoid spellcasters, creating random horrors from the lower planes, and more. If you are a game master, this is a must-have book for you.