We propose PORGY 1 a visual modelling framework (Fig. 1) designed for specifying, simulating , and analysing complex systems. PORGY is built on top of the open-source visualisation framework TULIP 2. PORGY is based on the use of port graphs with attributes to represent system states. In a port graph, edges connect to nodes at specific points, called ports. Nodes, ports and edges describe the system components and their relationships, while attributes encapsulate the data values associated with entity. We use graph transformations based on port graph rewrite rules to describe the evolution of the system. FIG. 1 – Overview of PORGY: (1) editing a graph; (2) editing a rule; (3) all available rules; (4) the derivation tree, a complete trace of the computing history; (5) editing a strategy.