Towards a Framework for Gamification Design on Crowdsourcing Systems: The G.A.M.E. Approach Crowd sourcing systems call a crowd of users to collaborate on solving real-life problems. One key issue for the success of such systems is to guarantee users’ participation. A strategy that has been used to promote user participation is the use of game design techniques, since games have successful strategies to grant enjoyable user experience. However, most gamification methods and guidelines are too generic, do not emphasize the collaboration aspects and focus on introducing rewarding elements into the application, instead of designing player-centric applications. Reward-based design is dangerous, specially for collaborative systems, because it may put points gathering as the primary purpose of the application instead of the collaboration goal. This paper presents G.A.M.E., a conceptual framework to guide the design of gamification in crowd sourcing-based systems. The framework provides a flexible step-by-step guideline that combines knowledge from software engineering, collaborative systems, game design and interaction design. To evaluate our proposal, we instantiated G.A.M.E. Into two applications in the domain of public transportation. The influence of gamification in those applications were evaluated through controlled navigation tests in a crowd sourcing usability testing platform. Our findings showed us that gamification improved user interfaces of collaboration activities by 16% on usability and were more trustworthy in 80% the cases.