A study published in a recent paper reveals some of the most influential papers in the gamification literature. It was very nice to know that my old contribution is still influential (“A social gamification framework for a K-6 learning platform”, available in academia.edu).
Details about the used measurement method can be found in the paper "Publication Trends in Gamification: A Systematic Mapping Study", by Jussi Kasurinen and Antti Knutas, Lappeenranta University of Technology, Finland. I made a review of this paper to Computer Science Review but lost track of if (not published?).