Smart city technologies offer the potential to address issues of sustainability and efficiency in cities. Continuous monitoring, geotracking and ubiquitous computing offer tools for engaging citizens, influence their behaviour and measuring its impact on the city. These technologies, however, are not neutral: if handled in a top-down way, give rise to many concerns (e.g. privacy, instrumentalist urban planning etc.). In this chapter, we illustrate an alternative, playful approach to urban sustainability, based on playable cities and on different ludic strategies. To do so, we will reflect on two playful artifacts created within the Mobility Urban Value (MUV) Project and aiming to make cities more sustainable. The first artifact in an app 1 that helps citizens in making sustainable mobility choices by transforming commuting in a gameful experience and rewarding sustainable choices. The second artifact developed within MUV is Asphyxia 2 , a screenless device simulating the breathing movements of living lungs as a poetic way of communicating air quality and presenting an artefact that is non-solutionist, open to interpretation, aesthetically complex, and playful. This chapter, hence, is built around: a reflective account of the ideation, design, implementation, and deployment of the two artifacts, a short set of "designer interviews" with their creators and an artefact critique / semiotic analysis of the various digital and physical artefacts composing this project. Drawing on these perspectives, the chapter will outline an approach for urban sustainability based on playfulness and ludicity.