The idea is to determine how game design can be applied to generate and sustain motivation in serious gaming, or applied gaming, design projects. Elements that spark a sense of playfulness embedded in an application in a non-game context have been shown to enhance the user’s engagement. DiabetesNinja is a healthcare app for children with type 1 diabetes, but the children who used it did not engage with it as they were meant to. When living with diabetes, one’s disease-related knowledge and self-management are important, but children can only learn these when they use and interact with the app properly and regularly. Therefore, as a part of learning to live with a chronic disease, the primary aim was to increase children’s motivation to use the application. This study explores relevant theories in the fields of gamification, pedagogy and healthcare. In this exploration, three co-design workshops were conducted to gain an understanding of the children’s current user experience, explore their attitudes towards game elements, and identify design possibilities. The outcome is a serious game design concept where diabetes index registration functions are embedded in the levelling up (bonus) system. In addition, the visually customizable Tamagotchi concept installed in the levelling-up system acts as an assistant to motivate the children on a regular basis and may contribute to the children's long-term engagement. I conclude with how the levelling-up system follows the pattern of diabetes data registration and is an appropriate game mechanic for both motivating children and easing their heavy cognition load in the disease-related index registration sequence.