Colossal Cave Collection (Paperback) (ISBN-13: 9780985009410)

This book contains 100 elegantly designed Cave puzzles from US Puzzle Champion Roger Barkan. The puzzles range from easy to hard in difficulty, with hints for each puzzle in case you get stuck in a cave. With a mixture of clever visual and logical themes, these puzzles will take you from a burrowing beginner to a spelunking superstar.