Early adolescence is a major time for friendship development, and interpersonal emotion regulation (iER) is a vital skill for social interactions. Serious games are an exciting way to engage young people with psychoeducational content. The authors developed a serious game teaching iER strategies to early adolescents in an interdisciplinary and participatory approach by working with industry professionals and including the target group throughout the development process. In a pilot feasibility study, player experience and the intended learning outcomes of emotion regulation were tested with 166 early adolescents. Results show positive player experience, with highest ratings in Usability, Personal Gratification and Enjoyment. Results about effects on emotion regulation (ER) are mixed, with personal ER increasing and iER decreasing. This shows the potential to include an engaging serious game in socio-emotional learning in schools, but also reveals several areas for improvement and the need for more rigorous testing in the future.