Game theory is a fascinating and tragically underrated field. This has much to do with mathematical abstraction and obscurantism. A "game" represents any scenario with two or more independent players, where each player's payoff depends on the combined choices of everyone.
This situation leads to easy mathematical modeling, but many real-world situations can also be represented as "games". For instance, "The Battle of the Sexes" is a game which models the competing entertainment choices of a couple who want to spend the night out on the town together. The game of "Chicken" can be used to model both the behaviour of teenagers or Cold War nuclear brinkmanship.
Dixit and Nalebuff explain games in terms of what they are to ordinary people -- simple stories illustrating the importance of strategic behaviour -- and not as abstract mathematical problems. They explain key points with examples from books, game shows, movies, and sport. They also show how a knowledge of game theory can come in handy when voting, bidding on eBay, or bargaining with others.
This book is essentially an updating and significant revision of their earlier book "Thinking Strategically". Thomas Schelling is an academic who takes a similar approach to game theory; his books are worth checking out if Dixit and Nalebuff manage to whet your appetite for the field.