Design research has increasingly taken an interest in inviting users and other stakeholders to contribute in the early phases of the design process. In the discourse of organising creative collaboration, design games have become a popular concept. The dissertation argues that in order to productively apply design games, it is important to understand their core identity by looking at the roots of the play atmosphere along with the play-qualities essential to it. This is done by studying games, play and performance separately and in connection with the application context, co-design.The three main perspectives adopted in this search are design collaboration, facilitating creative interplay between current practices and future opportunities, and design materials as tools in ideation. In doing so, this dissertation builds a Play framework that presents the elements and core qualities of design games in an extensive but compact way.