This paper describes three design values that we apply for designing playful interactions. Interactive play objects can stimulate social interaction and physical play by providing motivating feedback to players' behavior; they can allow players to create their own game goals and rules in an open-ended play context and support social player interaction patterns. This design approach is illustrated by six design cases in which our assumptions were examined in various play contexts. The results show that the application of these design values can lead to rich and appealing innovative play concepts. Players can create a wide range of (physical) games using open-ended play objects, and properties of the play objects, such as being personal or shared, influence the type of social interaction.