This book presents an overview of the emerging field of emotion in videogame soundtracking. The emotional impact of music has been well-documented, particularly when used to enhance the impact of a multimodal experience, such as combining images with audio as found in the videogames industry. Soundtracking videogames presents a unique challenge compared to traditional composition (for example film music) in that the narrative of gameplay is non-linear - Player dependent actions can change the narrative and thus the emotional characteristics required in the soundtrack. Historical approaches to emotion measurement, and the musical feature mapping and music selection that might be used in video game soundtracking are outlined, before a series of cutting edge examples are given. These examples include algorithmic composition techniques, automated emotion matching from biosensors, motion capture techniques, emotionally-targeted speech synthesis and signal processing, and automated repurposing of existing music (for example from a players own library). The book concludes with some possibilities for the future.