“…We instead refer to a subset of games that have a common clustering of mechanisms and business models that have become prevalent on mobile devices. What appears to be common among these is a reliance on principles derived from behavioral psychology, including the use of random ratio schedules of reinforcement alongside gambling themes, different types of reinforcement (e.g., achievements/badges) and the use of stamina-style systems to affect how frequently reinforcement is delivered ( James, O’Malley, & Tunney, 2017 ; Larche et al., 2017 ). These make heavy use of micro-transactions, often based on the premise that a small proportion of users, colloquially referred to as “whales” ( Alha, Koskinen, Paavilainen, Hamari, & Kinnunen, 2014 ; Kimppa, Heimo, & Harviainen, 2016 ), engage in substantial spending ( Garfield, 2016 ).…”