Serious games can be defined as abstracted representations (simulations) of our perceived reality which provide safe environments for exploration of that reality and learning. Consequently, serious gaming can be defined as an end-to-end collaborative and iterative process of delivering value with serious games. The essential component of that process are models of our perceived reality which are first used to guide a serious game design and then the translation of insights from a game run into action. This belief in the importance of models of reality was first triggered and then reinforced through my professional partnership and work with Richard D. Duke in the late 1980s and early 1990s. This chapter will reflect on the four essential requirements behind development of effective models of reality, all of which were a cornerstone of a serious gaming design approach promoted and used by Dick Duke: clarity of problem definition, thorough system analysis, collaborative and iterative development process, and the visual representation of the problem environment (the big picture).