Burgeoning research on innovation ecosystems ofers a variety of conceptual approaches. Recent systematic literature reviews and syntheses provide a rich, diverse, but somehow abstract view of IEs. Our study advances the literature by tak ing the perspective of those involved in IEs. We aim to identify how various actors contribute to co-innovation in innovation ecosystems. In order to do so, our aim is to establish the various types of actors (who?), the distinct roles (what?), the diferent stages (when?), and the diverse engagement in co-innovation processes (how?). The study investigates the Polish Gaming Innovation Ecosystem as a globally successful example of a knowledge-intensive and highly creative innovation ecosystem. Data was collected over 3 years (between 2015 and 2017), in three waves of interviews (38) and non-participatory observations (5). We fnd that Gaming Innovation Eco system participants identify a total of 12 types of collective actors, 9 types of indi vidual actors, and 1 community of individuals. Furthermore, we fnd four distinctive roles that actors may play in the co-creation processes, that is: direct value creation, supporting value creation, encouraging entrepreneurship, and leadership. Finally, we structure the co-innovation process into fve stages: co-discovery, co-development, co-deployment, co-delivery and co-dissemination. We identify the diverse scope and varied intensity of actors’ engagement, depending on the co-innovation phase, as perceived by our informants.