We present a novel playground platform that will hopefully help in countering two important issues in children in the developed world: lack of physical activity and lack of socialization. The system underlying the platform will eventually adapt automatically to and modulate the amount of physical activity of children by applying a new notion in interaction: that of "interaction tempo". The concept of beats per minute seems especially adequate as the base structure of a physically-based activity. As an exertion interface we expect that, through the design of collaborative experiences, it will also enhance socialization of children. Keywords Children, Playground, Interaction, Embodied, Physical Activity, Socialization, Exertion. ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous. K4.m Computing Milieux: Computers and Society: Miscellaneous. Copyright is held by the author/owner(s). CHI 2009, April 4 ? 9, 2009, Boston, MA, USA A...