In the context of the global trend towards urban densification, the space and quality of public outdoor play for children are declining. Malmö, the third-largest city of Sweden, is now facing such a problem. The purpose of this study is to investigate the impact of a themed playground (Rörsjöparken) in the city of Malmö on young children's play from a design perspective and to propose recommendations for optimizing this play space based on children's ideas in order to promote playful learning and optimal child development. Using affordance theory, this study analyses the impact of play space on children's interaction and use of space. It also explores how children's ideas can be organically integrated into the design and contribute to children's development through the application of a mosaic approach and the concept of the Urban Play Framework. The results showed that children could engage in more diverse types of play in natural spaces than in manufactured equipment spaces. The article recommends that designers incorporate four factors when assessing the quality of a play space in the early stages of design. These factors are: whether the play environment has 1. rich natural features, 2. suitable play equipment for children's abilities and physical conditions, 3. stimulating elements, and 4. high-quality parent-child interaction. Future studies are needed to explore approaches that can effectively consult children in large public outdoor play areas and investigate how to improve the children's play environment in winter.