In-App Purchase Behaviour and Game Design in Mobile Gaming: A Review of Monetisation and Player Experience

The rapid expansion of mobile gaming has driven the widespread adoption of in-app purchases (IAPs) as a dominant monetisation strategy. While this model enables scalable revenue through free-to-play experiences, it also raises significant behavioural, ethical, and regulatory concerns. This narrative review synthesises recent empirical and conceptual literature to examine the psychological and structural mechanisms that influence IAP behaviour, with particular emphasis on monetisation strategies, emotional engagement, and ethical implications. The findings reveal that monetisation systems such as loot boxes, premium upgrades, and psychological pricing often exploit reinforcement schedules and cognitive biases, leading to compulsive spending and reduced user trust. Emotional experiences such as flow, enjoyment, and hedonic satisfaction play a mediating role, influencing both purchase decisions and long-term retention. Furthermore, the ethical boundaries of these practices remain ambiguous, as many monetisation features mimic gambling structures and lack transparency. The study highlights a need for greater regulatory alignment, ethical design practices, and platform-level accountability. It also proposes future research directions involving trust, consumer autonomy, and the role of game context in monetisation outcomes. This review contributes to both marketing and game studies by advancing an integrated understanding of how design, behaviour, and monetisation intersect in mobile gaming environments.