Abstract - Serious Games (SGs) have been explored in healthcare for their potential as gamified means for disease assessment and/or intervention. Designing effective SGs requires attention to user requirements and iterative development. We introduce a SG design process for Psoriatic Arthritis (PsA) patients, aiming to enhance their quality of life. The latter is exemplified via “The Kite” Breathing SG, part of the Horizon Europe iPROLEPSIS project, which targets PsA symptoms, promoting relaxation and, potentially, alleviating stress and inflammation. Developed through an agile methodology, it engages patients, researchers, developers, and healthcare professionals in iterative co-design. Incorporating the “Liked, Learned, Lacked, Longed for” (4Ls) technique, feedback is systematically collected, refining designs and prioritizing user-centric features. Insights from 29 experts and patients led to the first working prototype of “The Kite” breathing SG. Ongoing work focuses on refining the game for clinical validation trials in ten months, emphasizing a comprehensive approach to SG design and development.