How to best develop educational computer games is an open question and an active area of research. It is clear that computer games are able to instill the desire for players to rise to challenges, learn new and complex skills, and most of all to be entertained. Researchers are now trying to identify the underlying motivational nature of computer gameplay to harness it for teaching and learning. This research explores the world of educational game design and development within the field of Serious Games, and presents the Structural Playability Process (SPP) for educational game design and implementation. Serious Games are games designed for a primary purpose other than pure entertainment. The development of the Structural Playability Process was undertaken through the design and production of two serious games; GeoThermal World, which provides a virtual geothermal field‐trip experience; and Ora – Save the Forest!, a simulation‐driven game for pest management in New Zealand forests. Using these games as case studies we describe the four SPP spaces of; education, translation, design, and engine, in support of research into the delivery of effective game design methods that facilitate engagement with educational topics. The main contributions of this research are in the development of a new, generalisable model of educational game design combined with a practical method for implementing the design into a game engine. The results infer that the SPP approach provides a means for ‘designing‐in’ conditions that can support motivation through ‘gameflow’ mapping, and provide support for the impact of serious games on learning; the games designed with the new model increased learning gains post‐play and supported knowledge retention. Finally, this research contributes empirical evidence to the field, as the SPP allows for the measurement of learning outcomes which are tracked throughout the design and development process.