Privacy Policy
Effective 24 October 2026
5D Chess Lab (fireplank.github.io/5d-chess-lab) is a free, non-commercial, open-source website for playing and studying 5D Chess With Multiverse Time Travel. Its source code is public at github.com/FirePlank/5d-chess-lab. This policy says what the site collects, why, who processes it, and how to have it removed. The site has no advertising, no analytics and no trackers, and it never sells or shares your data for marketing.
Using the site without an account
Most of the site (the analysis board, the board editor, the tutorial, practice, and games against the engine) runs entirely in your browser; your moves and analysis are not sent anywhere. The site keeps your settings, tutorial progress and the games you save in your browser's local storage, where only you can see them, and you can clear them at any time through your browser.
To play online and to keep a puzzle rating, your browser creates a random identifier (a "player token") and stores it locally. Our server only ever stores a one-way hash of it, which is not linked to your name or any other personal information unless you sign in.
Signing in with Discord or Google
You can sign in with Discord or Google to play rated games and keep a rating and a profile. Signing in is optional. When you do, the provider sends us, and we store:
- your account id at that provider (for Discord, your Discord user id);
- your display name and profile picture address;
- your email address (it is never shown to anyone, and we do not email you).
We use your Discord user id to look you up in the 5D chess community's existing rating list, so that a player who already has a community rating starts from it. We use your display name as your public name on the site. We do not request access to your messages, friends, servers, contacts, files or anything else at either provider, and we cannot post anything on your behalf.
What is public
Like other chess sites, online play is public by nature:
- your public name, rating and profile page, with your results and the games you played;
- the records of finished online games (moves, clocks, result, and both players' names and ratings);
- games in progress, which anyone can watch, and open games in the lobby.
Players who are not signed in appear as "Anonymous".
Everything we store, and why
| Data | Why |
|---|---|
| Hashed player token | To know which player is which in online games, puzzles and the lobby. |
| Account details from Discord or Google (above) | To sign you in, show your name, and carry over a community rating. |
| Your rating and rated results | To pair and rate games fairly and show your profile. |
| Games you play online, with move times | To run the game (clocks), keep its record, and show your history. |
| Chat messages in private games | To deliver them to your opponent during the game. |
| Short-lived presence pings (which page of the site a tab is on) | To tell a player who left a game from one who is still there; kept for a day. |
| Puzzle attempts | To rate puzzles and you, and not to repeat puzzles you have played. |
| How each of your turns went in online games against people: how long it took, how long the game's page was hidden or out of focus meanwhile, when you first touched the board, whether another tab of the same browser showed the game's live position on the analysis board or tried to run the engine, and a fingerprint of your browser (a hash of what it shows every website: its version, languages, screen, time zone and how it draws text) | Fair play: to detect engine assistance. Never public; kept for 180 days. |
| What the analysis board shows, as a hash of the position, with your browser's fingerprint (and your account, if you are signed in) | Fair play: only to notice an analysis board showing the live position of a rated game you are playing. Kept only when it matches (180 days); otherwise it is not stored. |
| Fair-play assessments of rated games, and any case opened about an account | Fair play. Only the site's admins can see them. |
| Engine crash reports: the error, the page and position it happened in, your browser's user agent, core count, memory and fingerprint, and your account if you are signed in | To fix the engine. Sent only when Kairos fails in your browser, posted to the admins' Discord channel, and kept for 90 days. |
Fair play. Using engine assistance in rated games is not allowed. After a rated game between two people ends, Kairos analyses it, as other chess sites do with their games, and an account whose play matches the engine's far more often than its rating explains is flagged for an admin to review. Nothing is decided automatically: an admin looks at the evidence before an account is barred from rated games. How the detection works is public (see the site's source code).
Who processes the data
- Supabase (supabase.com) hosts the database, sign-in and the online-play server.
- GitHub Pages (github.com) serves the website's files.
- Discord and Google handle sign-in when you choose them, under their own privacy policies.
- Discord also carries the admins' channel, where new fair-play cases and engine crash reports are posted.
These services see your IP address and browser details when your browser contacts them, as any website host does; we do not store IP addresses ourselves.
How long we keep it
Account data, ratings and game records are kept while the site exists or until you close your account. Presence pings are deleted after a day, and the turn measurements above after 180 days. Data kept in your browser stays there until you clear it.
Your choices and rights
- You can use almost the whole site without an account, and sign out at any time.
- You can close your account yourself (your profile → Edit profile → Close account): your account details, profile, rating, puzzle history and sign-in are deleted, and your finished games stay in the public record as played by "Anonymous". If an account barred from rated games for fair play is closed, a one-way hash of its sign-in identity is kept, so that the bar still applies to a new account made with it.
- You can change your name (once every 30 days) and your bio from Edit profile.
- You can ask for a copy of the data we hold about you, or for it to be corrected.
- You can revoke the site's access from your Discord or Google account settings at any time.
If you are in the European Economic Area or the United Kingdom, the GDPR gives you these rights, and the legal bases we rely on are performing the service you asked for (online play and accounts) and our legitimate interest in fair play. You may also complain to your data-protection authority.
Children
The site is not directed at children under 13, and we do not knowingly collect personal data from them. If you believe a child has signed in, contact us and we will delete the account.
Changes
We will post any changes to this policy on this page with a new effective date.
Contact
For questions, data requests or deletion, open an issue at github.com/FirePlank/5d-chess-lab/issues, or message the maintainer, FirePlank, on the 5D chess community Discord. For a private request, ask there for a private channel and do not post personal details in a public issue.