How Your Data Is Handled

Guest data stays in the browser.

For unsigned users, Earth Estimator saves game results and preferred game settings in the browser's local storage.

This means that the information is stored on the user's own device rather than in Earth Estimator's account database.

Information stored locally can include:

Game settings

Game mode

Selected countries

Selected themes

Previous game results

Because this information is stored locally, it can be more fragile.

Clearing browser data, changing browser or changing device can cause the locally stored information to disappear.

Signing in allows settings and results to be connected to an account instead of one browser.

To prevent game results and preferred settings from being lost, users have the option to identify themselves using either:

Earth Estimator uses Firebase Authentication, provided by Google, to handle this process.

Earth Estimator itself does not receive or store the user's plaintext password.

Instead, Firebase handles the authentication process and provides Earth Estimator with an authenticated user identity.

User
    ↓
Firebase Authentication
    ↓
Identity verified
    ↓
Firebase UID
    ↓
Earth Estimator

The Firebase UID is a unique identifier connected to the authenticated account.

Earth Estimator can then use that identifier to locate the correct user's saved data.

users/{uid}/gameResults

users/{uid}/settings

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Firebase Authentication listener

- Detect authenticated user
- Read user.uid
- Detect signed-out state
- Load account-specific data

Authentication identifies the user. Firestore Security Rules determine what that user is allowed to access.

Earth Estimator uses Firebase Firestore Security Rules to prevent one account from reading another account's data.

A simplified version of the rule looks like this:

allow read, create:
    if request.auth != null
    && request.auth.uid == userId;

Two conditions must therefore be true.

For example, imagine a user has:

That user can access data stored under:

users/abc123/

but should not be authorized to access data belonging to another Firebase UID.

For signed-in users, Earth Estimator may store:

• Email address
• Firebase user ID
• Game settings
• Selected game mode
• Selected themes and countries
• Number of questions
• Accuracy result from each completed game
• Game type
• Time the game was completed

Earth Estimator does not store a readable copy of the user's password in its Firestore database.

Firebase Authentication handles the password and authentication system separately.

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Example Firestore settings document

{
    gameMode: "...",
    selectedThemes: [...],
    selectedCountries: [...],
    numberOfQuestions: ...
}

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Example Firestore game result

{
    accuracy: ...,
    gameMode: "...",
    questionCount: ...,
    country: ...,
    clientPlayedAt: ...,
    playedAt: ...
}

The basic system can therefore be summarized like this:

Passwords
    → Firebase Authentication

User identity
    → Firebase UID

Game settings
    → Firestore

Game results
    → Firestore

Unsigned user data
    → Browser local storage

This allows Earth Estimator to keep guest data local while giving signed-in users a way to keep their settings and results connected to their account across different sessions and devices.