Understanding complex systems is a critically valuable skill across many domains, particularly in sustainability education Participatory simulations have often been used to provide learners with an “insider” perspective of complex systems – especially illuminating the emergence of certain behaviours as a result of local motivations. In this workshop, we invite attendees to playtest City Settlers – an embodied participatory simulation where participants control city-level systems and manage interdependent resources like materials, pollution, and people in a network of cities (controlled by "competing" players), in a classroom. This simulation is intended to provide a rich testbed for learners to build their understandings of complex systems, environmental education, as well as negotiation skills – where they figure out ways to negotiate and communicate shared as well as competing goals among each other. We also plan to share the kinds of data that a simulation of this kind generates from players (including play data, audio data, as well as in-class location data). This will be used to brainstorm ideas on how such data can be used for providing formative information to educators – about the kinds of productive collaborations taking place in their classrooms, and how to foster a greater variety of rich collaborative learning.