Guest progress is stored on your device. Optional Google sign-in uses Firebase Authentication. The game does not receive your Google password.
Registered accounts store a nickname, game progress, crystal totals and combat statistics in Firestore. Your nickname, UID, unlocked wave and kill counts are visible to other signed-in players in WORLD SCORE. Email addresses and private saves are not included in that table.
Sign-in between the game and your browser uses a short-lived encrypted transfer. Firebase session credentials are stored locally to keep you signed in. Resetting achievements retains your account and earned crystals; it is not account deletion.
On Android, optional update notifications check Google Play availability in the background. They can be disabled in Android notification settings. This feature does not send registration emails or store a push token.
Google Play purchases and advertising use their respective providers. To request account/data deletion, contact fisen1003@gmail.com.