A game-like, distributed application for learning code by playing.
Get it from Google Play.
The app requests access to the user account to simplify the collection of name/email in the Personalization screen. You can still set an alias name and email before connecting to the online server. Also, connecting to the online server (and thus registering to play with these credentials) is optional. In some cases, the app will ask you to fill in a questionnaire. These data are collected purely for research purposes. The questionnaire does not include your email, but it does include a unique ID (per installation) which is used to identify which answers come from the same users, and to correlate answers with performance.