Background: Adaptive interpersonal emotion regulation (iER) is a vital tool for positive relations. During early adolescence, peer relations become increasingly important, making this age group a relevant target group for interventions promoting positive interactions with each other, yet no evidence-based intervention exists for early adolescents specifically.

Methods: This randomized controlled trial (RCT) aims to test effectiveness and feasibility of a serious game training iER skills in early adolescents by comparing outcomes with a control group playing a game without psychoeducational content in a pre- and post-test design. German- and English-speaking early adolescents (10-14 years) are eligible for participation. IER skills improvement assessed by a vignette task is the primary outcome variable and will be analysed with a chi-square test. Feasibility and acceptability and variables such as emotional competence, personal emotion regulation, gender, and sex will be assessed by questionnaires.

Discussion: This RCT will test whether playing serious game about iER strategies will result in an improvement of iER skills and whether the game is feasible and acceptable for early adolescents with the ultimate aim to implement the game in school classes and help early adolescents achieve positive peer relationships.

Inclusion Criteria:

• Between 10 and 14 years old
• Willing and able to provide written parental consent
• Willing and able to participate in filling out pre- and post-test online questionnaires, and playing a web-based game
• Able to read and understand German or English
• Access to a device with internet (computer, mobile phone, tablet)

Exclusion Criteria:

-

Investigator and trial participants will be blinded throughout the study due to the automised randomization process via the online server SosciSurvey. Statistical analysis will be executed by generating a number for each group, with its affiliation unknown to the analyst.