Children and young people are very active users of digital technology from an early age. Recent research shows that children learn quickly from mirroring the behaviour of parents, of older siblings and peers. On one hand, children have acquired independency and skills within the digital world; on the other, they lack reflective and critical thinking as well as awareness about opportunities and risks such as cyber-bullying or digital identity theft. Active adult’s mediation would allow for the integration of values and critical thinking but so far, adults seem poor active mediators and in need of practical tools of empowerment. Therefore, we developed Happy Onlife, a game to support players towards a happy online life. This interactive video game aims at empowering teachers and parents to actively guide children to become smarter, responsible, and respectful when using digital media. We chose an experimental and empirical approach and the design of the game repeatedly undertook the elicitation, representation and validation steps. Happy Onlife presents key messages about children's use, overuse, and risks of misuse of digital technologies and provides simple and clear strategies of prevention, mediation or remediation. Tests beds have proved the efficiency of the video game’s questions to prompt discussion between generations and drives the players towards a responsible and safe digital media use. Happy Onlife can be considered as an effective tool to support adults’ mediation to children for a healthy and safe internet and digital technology use.