論文アブストラクト：Gamification and exergames in particular have been broadly employed in health and fitness as an attempt to promote exercise and more active life styles. Motivated by popularity and availability of wearable activity trackers, we present the design and findings of a study on the motivational effects of using activity tracker-based games to promote daily exercise. Furthermore, we have investigated user behaviors, usage patterns, engagement, and parameters that affect them. An exergame was developed with an accompanying wearable device, for which different variations of application updates were pushed out periodically over a 70-day period. The results of this long-term study show that the usage of wearable activity trackers during exercise, even when gamified for increased entertainment, sees a consistent decline over time. This decline, however, is observed to be reversible with periodic updates to the game. This work, we believe, can make a significant contribution to solving the user retention problem of wearable-based exergames.