In this paper, we present a case study of the mobile app and ecosystem Trafpoint. Trafpoint is a system for registering when and where people travel by public transport, using gamification in an attempt to convince more people to travel in environmentally friendly ways. We argue that the Trafpoint app is a good example of what we call “implicit participation”, where user-generated data from volunteers generate valuable input for the political decision-making process. With the growth of sensors, smartphones being ubiquitous, and the growing interest in the Internet of Things, this form of participation has the potential to become very valuable for decision-makers in the coming years.