Recently, several researchers have suggested that personalized game-ful systems can be more effective than generic approaches. However, there is still scarce empirical evidence that the suggested factors for personalization, such as gender, age, user types, and personality traits, will be effective in im-proving user engagement and performance for personalized gameful systems. In this work-in-progress, we present a research plan for empirical evaluation of a customizable gameful system. Upon completion of this study, we expect to pro-vide empirical evidence that the participants’ selection of gameful design ele-ments in a practical application will correspond to the theorized relationships suggested by prior survey-based research, and that the system can suggest the gameful design elements that users are more likely to enjoy. The results of this research will provide an actionable path for gamification designers to imple-ment personalized gameful systems and for researchers to develop recommen-dation algorithms for gamification.