Fitbit says it's working on enhancing the app experience to focus on providing its users with the best fitness tools, and its efforts to do so apparently include sunsetting a handful of features. Starting on March 27th, open groups, as well as all Fitbit challenges and adventures, will no longer be available on the Google-owned fitness company's app. The company said these features "have limited use," which likely means people haven't been using them enough to warrant their continued development and update.