Web-Based Narrative Game Intervention for Initiating Advance Care Planning Among Adults: Exploratory Cross-Sectional Feasibility and Acceptability Study.

BACKGROUND: Advance care planning (ACP) is an ongoing dialogical process. Despite growing policy-level recognition, ACP engagement remains limited in Japan, and many individuals remain unfamiliar with the concept. Beyond knowledge deficits, insufficient psychological readiness may also impede engagement. Evidence on fully online narrative- and game-based approaches to supporting such readiness remains limited. OBJECTIVE: This study aimed to explore the feasibility and acceptability of a fully web-based ACP educational intervention integrating an explanatory video and an interactive game and to evaluate postintervention cognitive, attitudinal, and psychological responses. METHODS: This exploratory cross-sectional online study was conducted in Japan between July and August 2025. The final analytic sample comprised 158 adults, including 46 with health care or long-term care experience and 112 without. Participants watched an animated explainer video, played an interactive narrative game, and completed a postintervention questionnaire online. Feasibility and acceptability were assessed based on participation and response distributions. Responses to 12 questionnaire items (Q7-Q18) were rated on a 5-point Likert scale. Between-group comparisons were conducted using 2-tailed Welch t tests (α=.05). Open-ended responses were organized into broad descriptive themes. RESULTS: Participants' mean age was 44.4 (SD 11.5) years, and 36.1% (57/158) were female. Postintervention responses showed generally favorable engagement. Mean scores exceeded the scale midpoint (3.0) for most items, including improved understanding of ACP (Q8: mean 4.39, SD 0.75), perceived importance of ACP (Q13: mean 4.42, SD 0.68), and personal relevance (Q15: mean 4.42, SD 0.83). Responses showed greater variability for imagining a concrete ACP discussion (Q17: mean 3.72, SD 1.02) and perceived psychological barriers (Q18: mean 3.49, SD 1.17). Significant between-group differences were observed for Q7 (mean difference -2.49, 95% CI -3.01 to -1.97; P<.001), Q10 (mean difference -0.40, 95% CI -0.71 to -0.09; P=.01), Q16 (mean difference 0.30, 95% CI 0.00-0.60; P=.048), and Q18 (mean difference -0.94, 95% CI -1.33 to -0.55; P<.001). CONCLUSIONS: A fully web-based, asynchronous ACP intervention combining explanatory video and an interactive narrative game may support early educational strategies that foster reflection on ACP. By engaging participants as active decision-makers in a simulated environment, the intervention provides preliminary evidence for psychological readiness as an educational outcome distinct from immediate behavioral change. Controlled longitudinal studies are needed to evaluate sustained behavioral outcomes.