Kids under treatments that involve long stays at a hospital or health center tend to get bored or depressed because of the lack of social interaction with family and friends. Such a situation also affects the evolution and effectiveness of their treatments. This article presents a mobile ubiquitous game called MagicRace, which allows hospitalized kinds to interact socially with one another, without putting to risk their sensitive health conditions. The game does not require a communication infrastructure at the hospital, but instead, it uses a mobile ad hoc network composed of the handhelds used by the kids to play. © 2012 Springer-Verlag.