## 5 Game Design of _Save the World of Naturalia!_  
### A Game for Therapy: Identifying Requirements  
One of the key components of the _SuperPowerMe_ monitoring system is the mobile video game _Save the World of Naturalia!_, an instance of games for health (G4H), which are explicitly designed to influence a person's health [27]. To ensure the game's effectiveness in a healthcare context, it is essential that the therapeutic requirements are rigorously considered. First, the game must align with the objectives of healthcare professionals and serve as a supportive tool to facilitate desired therapeutic outcomes [14]. Additionally, the game must adhere to the 'do no harm' principle, ensuring that it does not cause any negative psychological, emotional, or physical effects that could counteract its intended benefits. Therefore, a multidisciplinary approach is necessary to address such design-related challenges [28]. A comprehensive set of therapy requirements and game design considerations was established to guide the development of a therapeutic game aimed at treating Class III malocclusion in children (Table 1). The requirement for a nine-month therapy duration poses a significant constraint on the game's design, as the gameplay must align with the length of the treatment. From a game design perspective, this necessitates that the game is designed to last at least nine months, the expected duration for achieving therapeutic results. Furthermore, patients undergoing Class III malocclusion therapy are required to wear a facemask for at least 9 h daily. Therefore, an engaging reward system is critical to sustain children's motivation and compliance with wearing the facemask consistently. The second requirement pertains to the context in which playing takes place: the game should be simple enough for children to use it independently at home and should be designed so that children are not overexposed to the game, limiting screen time to maintain a healthy balance [29]. The third requirement relates to the target audience--school-aged children. Research has shown that the therapy is most effective when administered to children between the ages of 5 and 10 [30; 31]. This developmental period is crucial for cognitive, social, and moral growth, making it an ideal time to instil values and knowledge that shape future behaviours. For example, lessons about sustainability and environmental impact can inspire a sense of responsibility and purpose [32; 33]. Games for health are well suited to integrate such educational elements, extending the game's scope beyond merely achieving therapeutic objectives. With these considerations in mind, _Save the World of Naturalia!_ was devised by the designers in the project team as a therapeutic game specifically for Class III malocclusion treatment. The game is structured to create an engaging, playful experience that encourages compliance with the therapy protocol. Unlike traditional therapeutic games (e.g., exergames), the game's challenges and tasks are not directly tied to the therapeutic regimen. Instead, the game operates independently of the therapy, allowing children to play at any time, following the game's narrative and dynamics. In the context of orthodontic therapy, patients spend a considerable time passively wearing a facemask, time periods that are perceived as fruitless due to the manifestation of therapy results in the long term. For this reason, the game for therapy of our case study is designed as an idle game. According to [PERSON] et al. [34], idle games are characterised by four game dynamics:  
* Discovery: gradual unveiling of new content and mechanics as players engage with the game;
* Collecting: gathering 'vanity items' or virtual rewards;
* Progression: incremental progress in which both tokens and the effort to obtain them increase over time;