This game saves your game data to a server once every 15 minutes to back up your data. This contains your game progress and also an unique id depending on the platform where you play it. No personal data is taken. For Android the id from Google Play Games is used. If you didn't install Google Play Games, no backup will be made and no data taken. In Steam and Kongregate, the id from your login-name is used. This game recognizes your unique id and you may get your game save back if you lose it, or change your device as long as you log in with the same account and click 'Load Online' before the autosave takes place.
If you purchase something ingame, the item id, item cost, and time of purchase along with your user id may be saved to be able to protect against fraud and to analyze how well the purchases compare to each other.
The game collects data if, and when the game crashes along with some crashlogs, an id and device info.