Privacy at Cosmillion: no sign-up, local progress, transparent analytics

The short version

• No registration, email address, username or password is ever requested.
• Game progress — streak, scores, discoveries, badges and settings — stays in your browser's localStorage.
• Analytics is aggregate only: page views, sessions, approximate country, device class and referrer. Never your typed answers, prompts, scores, discoveries or email.
• No advertising, remarketing, heat maps, social embeds or data brokers.
• You can opt out per page with ?analytics=0, with Do Not Track, or by blocking googletagmanager.com.
• Clearing site data deletes your Cosmillion progress permanently.
• Questions? Write to hello@cosmillion.xyz.

What is stored on your device

Cosmillion saves your progress in localStorage under a single key: cosmillion:v1. This is a browser feature, not a server database: the data lives on your phone, tablet or computer, and it is not transmitted anywhere by the game. The saved record contains:

• Your current streak and best streak, plus the launch number you last completed.
• Your best score, total launches played and average.
• A local history of your daily results and the rarity tiers you hit.
• Your logbook discoveries — the rare answers you have found — and any badges earned.
• Your sound preference and, if you leave a launch partway through, an in-progress run so you can resume it.

That is the full list. There is no profile, no identifier, no email address and no game state stored on a server. Because the data is attached to the browser rather than an account, it is available to anyone who uses that browser profile — so if you share a device, use a separate browser profile or clear site data when you are finished.

What is sent over the network

The game itself is static. Loading a page requests its HTML, the shared CSS, the game JavaScript, two self-hosted font files and, when you play, the three daily data files from the same origin: /data/v1/manifest.json, /data/v1/schedule.json and /data/v1/bank.json. Those requests deliver the game; they do not upload your answers.

On the live production site, the page also enables Google Tag Manager (container GTM-KNQWWWFN), which loads Google Analytics 4 from Google's servers. Those requests go to Google, not to Cosmillion, and may include the page URL, referrer, an approximate location derived from your IP address, and device/browser information. Cosmillion never sends your typed answers, prompts, scores, discoveries or email address to analytics. Cloudflare also serves a small cookieless Web Analytics beacon on the same pages, which measures aggregate page views and Core Web Vitals without cookies or cross-site identifiers.

The site's Content Security Policy allows scripts only from Cosmillion, Google Tag Manager and Cloudflare's analytics beacon, with network connections limited to Google Analytics and Cloudflare endpoints — no advertising, social, heat-mapping or data-broker origins. You can confirm the requests in your browser's network panel.

Like any website, Cloudflare processes the HTTP requests needed to deliver files, which can include technical data such as an IP address and user agent for delivery and abuse protection. Cosmillion does not receive a per-player profile from that infrastructure data.

Opt out of analytics at any time: add ?analytics=0 to any Cosmillion URL (the preference applies to that page view), enable Do Not Track in your browser — which the site honours — or use Google's Analytics opt-out browser add-on. You can also block googletagmanager.com with any content blocker; the game keeps working.

Cookies and similar technologies

The game itself sets no cookies. Your only game storage is the single cosmillion:v1 localStorage key described above; it contains results, not identity.

When analytics is enabled on the live site, Google Analytics 4 sets first-party analytics cookies named _ga and _ga_<container>. They distinguish sessions so we can count visits and see which pages are useful. They are not used for advertising, remarketing or cross-site personalisation, and Cosmillion does not sell or broker the data.

Because the site has no account, no ad personalisation and no profiling, it does not show a cookie wall. You can still opt out: ?analytics=0, Do Not Track, blocking googletagmanager.com, clearing cookies for cosmillion.xyz, or Google's opt-out add-on. The only query parameter the game itself understands is the challenge code used by challenge links, which encodes a launch number and a score — no answers, prompts or player identifier.

Analytics and advertising

Cosmillion uses Google Tag Manager (container GTM-KNQWWWFN) to deploy Google Analytics 4. The purpose is aggregate measurement: page views, sessions, approximate country, device/browser class and referring site. We use it to understand which pages and modes players find useful and to catch broken deployments. We do not send prompts, typed answers, scores, discoveries, streak data or email addresses to analytics.

Google acts as our analytics processor; its handling is described in Google's privacy policy at policies.google.com/privacy. Retention follows the Google Analytics property setting. We do not enable advertising, remarketing or audience sharing in the container, and no analytics data is sold.

Cloudflare Web Analytics is also active. It is cookieless: it counts aggregate page views and performance metrics for the host and sets no cookies or identifiers of its own. It is infrastructure-level measurement from our CDN provider, not advertising.

Advertising: there is none. No ad networks, affiliate pixels, heat maps, social embeds or data brokers are loaded. If any of this changes, this page will be updated before the change ships.

If you email us

The site lists one contact address: hello@cosmillion.xyz. If you write to it — a bug report, a prompt suggestion, a privacy question — the message and your email address are used only to read and reply to you. They are not added to a mailing list, not passed to a third party for marketing and not attached to a game profile, because there are no game profiles. Ask us to delete a support thread and we will.

Cosmillion does not knowingly collect personal information from children. There is no account system, no chat, no user-generated content and no data collection to consent to, which is why the game can be played without any sign-up at all. If you believe a child has sent us personal information by email, contact us and we will delete it.

Your choices and rights

Because Cosmillion holds no personal data on a server, most data rights are exercised directly in your browser. You can view your stored progress in your browser's developer tools, clear it through browser settings, or stop using the site at any time. There is no account to delete and no data export to request.

If you are in a jurisdiction with specific privacy rights — for example under the GDPR or CCPA — the position is: we hold no account or game profile, we do not sell or share personal information, and the only personal data we may hold directly is an email you choose to send us. Aggregate analytics data is processed by Google as described above; you can opt out at any time. You can ask what we hold, or ask us to delete it, by writing to the address above.

Changes to this policy

If the game's data practices change, this page will be updated with a new effective date before the change is deployed. The current version, effective 7 November 2026, describes a game with no accounts, local progress and aggregate Google Analytics 4 measurement that you can opt out of. Questions about anything on this page are welcome at hello@cosmillion.xyz.

For how the game itself works, see how to play Cosmillion. For the longer design story behind the daily format, see the daily word game page.