This study aims to examine the effects of playable advertising characteristics on mobile game usage intention and to explore the mediating role of self-efficacy in this process. While previous studies have primarily focused on the effects of interactivity and experiential features of playable advertising on users’ immediate responses, this study structurally investigates the process through which cognitive and psychological perceptions formed during the advertising experience lead to usage intention. Drawing on Social Cognitive Theory, this study utilizes the perspective that individuals’ behavioral performance is shaped through the interaction of environmental stimuli, cognitive judgments, and psychological factors such as self-efficacy as the foundation for theoretical discussion. Based on this perspective, the Extended Technology Acceptance Model (ETAM) is adopted as the theoretical framework to analyze how perceived usefulness, perceived ease of use, and perceived enjoyment are related to mobile game usage intention through the mediating role of self-efficacy. An online survey was conducted with 179 smartphone users aged 20–39 who had experienced playable advertisements within the past month, and the hypotheses were tested using structural equation modeling and bootstrapping techniques. The results indicate that perceived enjoyment and perceived ease of use show indirect associations with mobile game usage intention through self-efficacy, whereas the mediating effect of perceived usefulness is not statistically significant. These findings suggest that, in the context of playable advertising, the formation of usage intention may be more closely related to affective responses and perceptions of behavioral capability developed during the advertising experience than to perceptions of functional usefulness. By focusing on self-efficacy as a key psychological factor, this study provides foundational insights into understanding the process of usage intention formation in experiential advertising contexts.