This book examines the evolution of digital platform economies through the lens of online gaming. Offering valuable empirical work on Valve's 'Steam' platform, Thorhauge examines the architecture of this global online videogame marketplace and the way it enables new markets and economic transactions. Drawing on infrastructure, software, platform and game studies, the book interrogates the implications of these transactions, both in terms of their legality, but also in how they create new forms of immaterial labour. Shedding new light on a previously under-explored branch of the study of digital platforms, this book brings a unique economic sociology perspective into the growing literature on videogame studies.