Population aging poses growing challenges for healthcare systems, driving the search for technological solutions that promote cognitive health, autonomy, and quality of life for older adults. In this context, serious games have emerged as a promising alternative for cognitive assessment and stimulation by integrating motivation, learning, and monitoring into more engaging and less invasive experiences. This study presents a systematic mapping of the literature on UX evaluation in serious games focused on cognitive health for older adults, covering publications from 2020 to 2025 indexed in Scopus, Web of Science, and PubMed, from which 96 primary studies were selected and analyzed. The results show that UX evaluation is primarily grounded in established models, such as the Technology Acceptance Model, Self-Determination Theory, Flow models, and Cognitive Load Theory, which are predominantly applied in a partial manner. Traditional clinical instruments (e.g., MoCA and MMSE) and usability metrics (e.g., SUS) predominate, ensuring clinical rigor but often overshadowing emotional, contextual, and experiential aspects. While usability and engagement are widely prioritized dimensions, emotion is increasingly gaining relevance, whereas critical dimensions such as accessibility and trust remain underrepresented. Although multimodal approaches based on digital biomarkers and machine learning show growing potential, their adoption is still limited and heterogeneous. These findings highlight the need for integrated UX evaluation frameworks that articulate the clinical, experiential, and multimodal dimensions, thereby informing the design of serious games that promote cognitive, emotional, and socially meaningful experiences for older adults.