Welcome to the third installment of my four-part article series on the core principles of music interactivity, including video demonstrations and supplementary supporting materials that take these abstract concepts and make them more concrete. In Part One of this series, we took a look at a simple example demonstrating the Horizontal Re-Sequencing model of musical interactivity, as it was used in the music I composed for the Speed Racer Videogame from Warner Bros. Interactive. Part Two of this series looked at the more complex Horizontal Re-sequencing music system of the Spore Hero game from Electronic Arts. So now let’s move on to another major music interactivity model used by video game composers – Vertical Layering.