The growing importance of collaborative or group decision-making in business projects is accompanied by several challenges, mainly cognitive biases. This paper focuses on identifying the key biases that affect group decision-making and explores the potential of serious games as a training method to address these issues. Using a design science research methodology, a game prototype was developed to improve group decision-making in corporate environments by increasing players’ awareness of bias-influenced decisions. The findings indicate that there is a need to provide specifically designed games for team-based decision-making, and only a limited number of existing games are specifically designed for corporate decision-making contexts. Our contribution addresses the lack of integrated training tools that increase cognitive bias awareness for decision making in projects, demonstrating the potential of a collaborative serious game to mitigate biases such as groupthink bias, authority bias, and social loafing while providing actionable insights for enhancing its design and effectiveness. It shows that every bias requires specific game characteristics, such as storyline, feedback mechanisms, and role concepts.