The chapter sets the scope, rationale and purpose of the book. It then covers a number of related topics, principally a review of learning theories and considers Bloom's well known learning taxonomy, and at which levels games of the mixed reality genre can be associated. The impact of games and simulations in learning is backed up by evidence from a survey of opinions as to which types of learning raise achievement levels the most. It also introduces the concepts of Experiential Learning (EL), Problem Based Learning (PBL) and Simulation Based Training (SBT) and then considers recent developments in education such as digital games, e-learning, distance and blended learning. It concludes with a review of earlier assessments of the value of games and an introduction to the suggested elements of good design in mixed reality games.