1. Institute of Educational Technology, National Research Council of Italy, Genoa, Italy
2. Game Science Research Center, Lucca, Italy
3. V. I. E. (Valorizzazione Innovazione Empowerment) s.r.l., Genoa, Italy
4. Centro di Ricerca sul Gioco, University of Genoa, Genoa, Italy
5. Computer Science Department, University of Milan, Milan, Italy