YAOKU Lattice Sums

Terms of Service

Effective date: upon owner-approved publication of these revised Terms on playyaoku.com.

YAOKU at playyaoku.com is operated by Elijah Maxwell. These Terms govern your use of the website, puzzles, sharing features, optional accounts, and leaderboards (the “Service”). “YAOKU,” “we,” “us,” and “our” refer to Elijah Maxwell as the operator of YAOKU. By using the Service, you agree to these Terms to the extent permitted by applicable law. If you do not agree, do not use the Service. Questions may be sent to terms@playyaoku.com.

1. Eligibility

YAOKU is for people age 13 and older. We do not knowingly allow children under 13 to use our services. Children under 13 must not use the Service, even with parental permission. If you are at least 13 but have not reached the age of legal majority where you live, you must have a parent’s or guardian’s permission, and they should review these Terms with you.

The website does not verify ages or provide a parental-consent process. To create an optional account, you must self-attest that you are 13 or older; the server requires this confirmation and records when you make it, but it does not verify your age. This minimum-age rule is not a promise of technical age enforcement.

2. The game and your saved records

YAOKU has one game, the Daily. The server chooses three puzzles (Easy, Medium, and Hard) for each calendar day in America/Chicago and is authoritative: everyone receives the same puzzles for the same day, changing at Chicago midnight including daylight-saving-time changes. Daily puzzles have a verified unique solution. Playing does not require an account. Optional accounts add official, server-timed results and public leaderboards. The Service does not offer payments.

Puzzle state, entries, notes, elapsed time, hints, completion records, and preferences from guest play are saved locally in your browser. They are not automatically synchronized between devices or backed up to a YAOKU account. Changing devices, using private browsing, browser storage limits, or clearing site data may make those records unavailable. We do not guarantee their preservation or recovery.

If you create an optional account, keep your devices and passkeys secure: anyone who can use one of your passkeys can use your account. There is no email or password recovery, so losing every passkey may mean losing access to your account. Your username and official results are public. Daily standings are grouped by Chicago date and difficulty and are viewable for the most recent 30 Chicago dates. Weekly standings are grouped by difficulty and UTC week (Friday through Thursday), count one official completion per account, difficulty, and UTC date, and earlier weeks remain viewable. Account deletion removes your official results and Weekly Leaderboard entries from YAOKU’s standings, but cannot remove copies others have made. Server timing and checks do not prove that a result was achieved unaided or guarantee fair play.

Difficulty labels are provisional estimates, not guarantees of difficulty or suitability. Availability of a puzzle, feature, account service, leaderboard, or storage capacity is not guaranteed.

3. Sharing results

After finishing a Daily, you can share a text summary of your result. It is created on your device and never includes the puzzle’s digits. Do not treat sharing as a confidential messaging feature.

The earlier shared-puzzle links (/p) and result links (/r) have been retired and now open the home page. See the Privacy Policy for how puzzle definitions saved by that earlier feature are handled and how to ask about their removal.

4. Permission to use the Service

We give you a limited, nonexclusive, nontransferable permission to use the Service for personal, noncommercial purposes in accordance with these Terms and applicable law. You may use the built-in sharing features and share links to YAOKU. This permission does not transfer ownership of Service content or grant rights in material belonging to others.

Except as permitted by law or with the relevant rights holder’s permission, do not copy, sell, redistribute, or commercially exploit the Service’s content. For licensing or business-use questions, contact business@playyaoku.com.

5. Acceptable use

Do not use the Service unlawfully, infringe another person’s rights, introduce malicious code, attempt unauthorized access, or disrupt, overload, or interfere with its operation or security. Do not use automated requests in a way that harms availability or attempts to bypass reasonable security restrictions. Ordinary assistive technology and accessibility use are not prohibited by this rule.

We may take reasonable, proportionate steps to address misuse or protect the Service, including restricting access where reasonably necessary.

6. Ideas and feedback

If you submit puzzle ideas, feedback, or suggestions, you retain any ownership rights you have in them. You give us a nonexclusive, worldwide, royalty-free permission to evaluate and use the submission to develop and improve YAOKU. Do not submit confidential information or material you do not have permission to share. This permission does not transfer ownership of your other content or override the Privacy Policy.

7. Privacy and other services

Our Privacy Policy describes browser storage, sharing, optional accounts and leaderboards, hosting, and correspondence. The site uses Cloudflare infrastructure. Cloudflare’s services, your passkey provider, and any third-party sites you choose to visit may be subject to separate terms and privacy policies.

8. Availability and warranties

We may change, suspend, or discontinue features or the Service for operational, security, or other reasonable reasons. To the fullest extent permitted by applicable law, the Service is provided “as is” and “as available,” without warranties that it will be uninterrupted, error-free, or suitable for a particular purpose. We disclaim implied warranties and conditions only to the extent that the law allows.

Nothing in these Terms excludes a warranty, consumer guarantee, or other right that cannot lawfully be excluded.

9. Liability

To the fullest extent permitted by applicable law, we are not liable for indirect, incidental, special, consequential, or punitive losses, or loss of data, arising from use of or inability to use the Service. This limitation does not apply where the law prohibits it and does not exclude mandatory consumer rights or remedies. Nothing in these Terms limits liability that cannot lawfully be limited.

10. Changes and ending use

We may update these Terms prospectively by posting the revised wording with an effective date before the changes take effect. Where the law requires additional notice or agreement, we will not rely on posting alone. Continuing to use the Service after revised Terms take effect constitutes acceptance only to the extent permitted by applicable law.

You can stop using YAOKU at any time. If you created an optional account, you can delete it from your profile after a recent passkey sign-in and username confirmation. Deletion removes the account, its passkeys, sessions, attempts, official results, and Weekly Leaderboard entries from YAOKU; it does not delete guest progress saved in your browser or copies already made by others. If you do not accept revised Terms, stop using the Service. Provisions that by their nature should continue, including permissions concerning submitted ideas and legally valid limitations, continue as applicable.

Mandatory rights and protections under applicable law remain unaffected. If a provision is unenforceable, the remaining provisions continue to apply to the extent permitted by law. These Terms do not select a particular governing jurisdiction or require arbitration.

11. Contact

Operator: Elijah Maxwell, operating YAOKU.