A call for robust evaluations of the impacts of serious games for climate change mitigation: example with The Climate Fresk conducted among 2 million participants from 150 countries

Serious games and gamified workshops are increasingly used in sustainability education, yet their actual cognitive, emotional, attitudinal, and behavioral impacts remain under-evaluated. The Climate Fresk is a widely implemented example, with over two million participants in more than 150 countries. Designed to raise climate awareness through collaborative learning and emotional engagement, its growing popularity contrasts with the limited scientific assessment of its effectiveness. This perspective paper uses The Climate Fresk as a case study to examine the broader challenges of evaluating serious games in climate education. Drawing on insights from environmental psychology, educational and behavioral sciences, we analyze its potential mechanisms of action, identify key moderating factors, such as participant characteristics, facilitator attributes, and implementation context, and highlight limitations in current evaluation practices. We conclude by outlining a research agenda that emphasizes the need for rigorous, theory-driven experimental designs, including randomized controlled trials focused on relevant psychological determinants of behavior change. Such efforts are essential to establish the evidence base required to improve the effectiveness, reproducibility, and scalability of gamified climate education interventions.