Terms of Service

Last Updated: May 31, 2026

Product / brand: YiChess Product website: https://yichess.com Operator and seller-facing entity: Vistasense AI Technology Limited, a Hong Kong limited company, Company No. 80364727, Business Registration Certificate No. 80364727-000-05-26-8, registered address: Room 1602, 16/F, Wing On Centre, 111 Connaught Road Central, Hong Kong. Support: support@yichess.com

1. Acceptance of these Terms

These Terms of Service (the “Terms”) govern your access to and use of YiChess, a web-based Chinese chess learning software, AI-powered post-game review and digital education platform for international users.

By creating an account, signing in, accessing learning content, purchasing a subscription, using AI review features, using training tools, using course packs, using practice features or otherwise using the platform, you agree to these Terms. If you do not agree, you must not use the platform.

If you use the platform on behalf of an organization, you represent that you have authority to bind that organization. These Terms apply to all users, including free users, trial users, paying users and account administrators.

2. Who We Are

Vistasense AI Technology Limited operates the overseas product website, user accounts, subscriptions, customer support, payment-related customer front, product catalog and platform policies for YiChess.

Certain core technology, software, AI analysis systems, learning content, product materials, brand assets, domain-related assets, engineering support, hosting support, security support or product support may be owned, controlled, licensed or provided by Hangzhou Weishi Information Technology Co., Ltd. or other technology providers under separate commercial, license or intercompany arrangements.

For purchases processed by Paddle, Paddle may act as the Merchant of Record, reseller or payment/seller of record as shown at checkout and on receipts. For purchases processed directly by Vistasense AI Technology Limited through Stripe, bank transfer or another approved method, Vistasense AI Technology Limited may act as the seller or invoice issuer unless otherwise stated at checkout.

3. Eligibility and Territory

You must be at least 13 years old to use the platform. If you are under the age of majority in your country or region, you may use the platform only with the consent and supervision of a parent or legal guardian.

The platform is intended for users outside mainland China. We may restrict access, payments or features in certain countries or regions because of legal, sanctions, payment, export control, tax, age, content, product or risk requirements.

You must not use the platform if you are prohibited from doing so under applicable law, sanctions rules, payment provider rules or these Terms.

You may create or access an account using one or more methods made available by us, including email/password, email verification code, magic link and/or Sign in with Google.

If you use Sign in with Google, Google authenticates your Google Account and may share limited account information with us, such as your Google account identifier, email address, email verification status, name and profile image. Google does not sponsor, endorse or control YiChess, our courses, AI review, practice features, subscriptions, customer support or platform policies.

You are responsible for keeping your credentials secure. You must not sell, rent, transfer, share or make your account available to another person without our prior written consent. You must notify us promptly if you suspect unauthorized account access.

We may require email verification, re-authentication, two-step checks, risk checks or additional security steps before allowing access to paid features, account changes, password resets, Google account linking/unlinking, account deletion, payment changes, high-risk activity or other sensitive actions.

5. Platform Features

The platform may include self-paced Chinese chess lessons, rules, strategy content, training exercises, puzzles, AI-powered post-game review, analysis reports, learning reports, progress tracking, course packs, membership features, free practice tools, non-cash practice features, customer support and other related digital education or software features.

Paid products are limited to digital subscriptions, digital course packs, AI-powered post-game review software, AI review quotas for educational post-game analysis, training tools, puzzles, progress tracking and learning reports.

If non-cash practice matches or similar play features are available, they are auxiliary learning, training and entertainment features only. They are not monetized through entry fees, are not prize-based, do not produce cash or cash-equivalent rewards, do not permit withdrawal, do not involve betting or wagering, and are not connected to real-money gaming.

6. No Gambling, No Real-Money Gaming and No Cash-Out

YiChess is not a gambling, betting, wagering, casino, lottery, sweepstakes, cash-prize, cash-game, real-money gaming, money transmission, stored value, token trading, virtual asset, investment or cash-out platform.

The platform does not support cash prizes, prize pools, paid competitions with prizes, betting stakes, wagering, redeemable points, deposits, withdrawals, stored value, wallet balances, user-to-user money transfer, crypto or USDT settlement, virtual currency exchange or third-party real-money gaming integrations.

Any attempt to use the platform for gambling, betting, wagering, cash-out, money transmission, prize pools, paid competitions with prizes or real-money gaming is strictly prohibited and may result in immediate restriction, suspension or termination.

7. AI Review and Educational Use

AI review, move explanations, evaluations, training recommendations, scores, labels and generated learning content are provided for educational and training purposes only. They may be incomplete, inaccurate, delayed, biased or unsuitable for a particular game, player, rating level, device, jurisdiction or learning objective.

AI review is not professional advice, official arbitration, tournament adjudication, a guarantee of winning, a promise of rating improvement or a commitment that any move is objectively best in all circumstances.

AI review must not be used as real-time assistance during live games, competitions, examinations, rated events or any setting where external assistance is prohibited. We do not provide real-time AI assistance, best-move overlays, engine overlays or cheating assistance during live play.

8. Fair Play and Prohibited Assistance

You must play fairly and use the platform honestly. You must not use chess engines, bots, scripts, automation, overlays, screen assistance, unauthorized external tools or another person’s real-time help during restricted play modes.

You must not collude, manipulate ratings, boost accounts, sandbag, create throwaway accounts to evade enforcement, exploit bugs, abuse latency or disconnection rules, harass users, impersonate others or engage in any conduct that undermines fair play.

We may use automated systems, technical signals, game patterns, statistical indicators, device/session signals, user reports and manual review to detect abuse and enforce policies. We may restrict access to detailed detection methods to protect anti-cheating systems.

9. Subscriptions, Digital Products and Entitlements

Paid features may include recurring subscriptions, time-limited memberships, digital course packs, AI review quota packs and other digital entitlements.

AI review quotas, learning credits, membership access and service entitlements are non-transferable, non-withdrawable, non-redeemable for cash, have no monetary value outside the platform and may only be used within the platform according to the applicable product rules.

Prices, billing cycles, renewal terms, taxes, payment methods, cancellation paths, refund rules and provider terms will be shown at checkout, in account settings, in the applicable Subscription Terms or by the relevant payment provider.

You must not abuse refunds, chargebacks, trials, coupons, payment disputes, subscription cancellation flows or promotional offers.

10. Payments and Payment Providers

Purchases may be processed by Paddle, Stripe, banks, EMI partners or other approved providers.

When Paddle is shown at checkout as Merchant of Record, reseller or payment/seller of record, Paddle may handle payment collection, transaction taxes, receipts, refunds and chargebacks under Paddle’s own terms and buyer support process.

When Stripe or another direct payment provider is used and Vistasense AI Technology Limited is shown as seller or invoice issuer, Vistasense AI Technology Limited may act as the seller or invoice issuer unless the checkout flow states otherwise.

We do not accept personal payment collection codes, private transfers to staff, employee accounts, friends’ accounts, personal Alipay/WeChat collections, crypto/USDT settlement, informal deposits or off-platform payments.

11. Refunds and Cancellations

Refunds and cancellations are governed by our Refund Policy, Subscription Terms, checkout terms, mandatory consumer laws and applicable payment provider rules. For Paddle purchases, Paddle’s buyer terms and support process may also apply.

A cancellation stops future renewal but does not automatically refund past charges unless required by law, stated at checkout or allowed under our Refund Policy.

12. Acceptable Use

You must use the platform lawfully, fairly and responsibly. You must not attack, scrape, reverse engineer beyond lawful limits, overload, disrupt, bypass security controls, abuse login flows, enumerate accounts, upload infringing content, distribute malware, harass users, impersonate others, violate sanctions or export rules, misuse customer support or use the platform in a way that harms users, the platform or third parties.

You must comply with our Acceptable Use Policy, Fair Play Policy, No Gambling Statement and other posted policies.

13. User Content

If you upload, submit, post, chat, comment, import game records or otherwise provide content to the platform, you represent that you have the necessary rights to do so and that the content does not violate law or third-party rights.

You grant us a worldwide, non-exclusive, royalty-free, transferable and sublicensable license to host, store, reproduce, display, analyze, moderate, remove, transmit and use your content as reasonably necessary to operate, secure, improve and provide the platform, enforce policies, provide support and comply with law.

14. Intellectual Property

The platform, software, interface, product design, AI review workflow, learning content, course materials, training exercises, databases, trademarks, logos and related materials are owned by or licensed to Vistasense AI Technology Limited, Hangzhou Weishi Information Technology Co., Ltd. or their licensors.

Subject to these Terms, we grant you a limited, revocable, non-exclusive, non-transferable and non-sublicensable right to use the platform for personal learning, training and permitted educational use.

You must not copy, resell, redistribute, commercially exploit, scrape, train competing systems using unauthorized extraction, remove notices, bypass access controls or otherwise misuse our intellectual property.

15. Open Source

The platform may use open-source components. Certain Chinese chess engine analysis features may interact with Pikafish or other open-source components. Open-source components are subject to their own licenses and notices. See our Open Source Notice.

16. Suspension and Termination

We may warn, restrict, suspend, terminate or refuse service to accounts, subscriptions, features or transactions if we reasonably believe that you violated these Terms, platform policies, payment provider rules, fair play rules, security rules, age requirements, law or third-party rights, or if necessary to protect users, payment integrity, the platform or third parties.

We may deny refunds where permitted by law and policy if the account was suspended for cheating, fraud, abuse, chargeback abuse or serious violations.

17. Disclaimers

The platform is provided on an “as is” and “as available” basis. We do not guarantee uninterrupted access, error-free AI outputs, match availability, ranking accuracy, learning outcomes, revenue outcomes, rating improvement, compatibility with every device or availability in every country or region.

18. Limitation of Liability

To the maximum extent permitted by applicable law, we are not liable for indirect, incidental, special, consequential, exemplary or punitive damages, loss of profits, loss of data, loss of goodwill, service interruption, AI output errors, match results, user conduct, third-party provider failures or events outside our reasonable control.

Where liability cannot be excluded, our aggregate liability will not exceed the greater of USD 100 or the amount you paid to us or through the platform for the relevant product in the three months before the event giving rise to the claim, unless mandatory law requires otherwise.

19. Changes

We may update these Terms from time to time. If changes are material, we will take reasonable steps to notify users, such as by posting an updated version, displaying an in-product notice or requesting renewed consent where required.

20. Governing Law and Disputes

These Terms are governed by the laws of Hong Kong, without regard to conflict of law rules, unless mandatory consumer protection law in your country or region requires otherwise.

Subject to mandatory consumer rights, disputes will be submitted to the courts of Hong Kong. Nothing in these Terms limits non-waivable consumer rights or regulatory rights that apply in your country or region.

21. Contact

General support: support@yichess.com Legal notices: legal@yichess.com Privacy requests: privacy@yichess.com Billing support: billing@yichess.com