Understanding and modeling complex ecosystems, where a great number of entities interact in different ways, is a great challenge in the information systems' domain. In this context, the InnoServ project aims to understand and support innovations around fragile people considering public, private and volunteering structures. The aim of this paper is to present the ADInnov method, which facilitates the analysis, the diagnosis and the proposition of innovations for complex ecosystems. This method has been extracted in an empirically way, from the lessons learned in the InnoServ project combining different techniques such as expert interviews, goal modeling and serious games. This method could be used in other areas where it is necessary to analyze complex ecosystems. Drawing out and discussing the results of the InnoServ project, we prove the efficiency of our method.