Moral courage has rarely been the focus of persuasive technologies. So far, few insights on persuasive strategies for moral courage exist, which mainly target a social psychological perspective but do not address game-based specifics. Against this background, we conducted an experimental study to identify game-related persuasive strategies. We show that the players’ experience of relatedness, i.e., social belonging and interactions with fictitious characters or other players, is key for enabling courageous altruistic behavior change, namely moral and civil courage, but not other forms of altruistic behavior, such as help-giving. We present large to medium effect sizes with an increase in the relationship between moral courage and relatedness over time. We conclude that persuasive technologies for moral courage require specific persuasion strategies. By addressing relatedness, users can negotiate social norms in a reciprocal relationship with the technology, and future persuasive games could contribute to increased moral courage and, thus, social justice.