This article explores how incorporating game-based formats and playful practices into the design process can inform urban and architectural design. The role of play in design is examined according to three aspects: constraints (facilitating an explorative use of factual or self-imposed constraints); engagement (prompting new types of engagement and authorship through dialogism); and chance (creatively embracing chance). Through a series of case studies, this paper investigates a range of possibilities for introducing play into spatial design practice and reflects on how it can serve as a foundation for rethinking authorship in design.