The mobile app uses local storage to track which scavenger hunt objectives you have found. It stores only the objective code number. The app does not track any information about users, beyond what is in standard web server logs. Opting out of playing is also not tracked so that you can choose to play at any time.
Each badge stores whether you are a guest or staff, the Daleks you interact with, the games you play (and how many you win), and the objectives you find. When you print your Dalek's adventures, that information is used to generate the story, and is copied to our database to generate the leaderboard, and to free up space on the Dalek for more adventures. We do not collect any additional information from guests, and cannot identify who has which badge.