As people get older, their physical and cognitive functions decline. Meeting these needs is an important goal to be reached, to propose activities that may contribute to a better quality of life, including leisure and learning. As such, this paper aims to present a set of heuristics and recommendations for the design of mobile serious games for older adults. To elaborate these heuristics and recommendations, we conducted two studies with older people. In the first study, we invited people aged 60 or more to evaluate mobile games, intending to collect data that could help us to adapt the heuristics that were already published to the public of this research. In the period between the two studies, we developed a serious mobile game (Labuta Batuta) that met the set of adapted heuristics. In the second study, we invited another group of older people, aged 45 or over, to qualitatively evaluate Labuta Batuta, in order to develop a Grounded Theory about the desirable characteristics for the design of serious mobile games for older adults. Besides a Grounded Theory, the second study allowed the identification of nine requirements to be considered when designing the mechanics of mobile games for older adults.