Terms of Use

1. The Service and Acceptance of These Terms

PastEcho (the “App”) is an AI-powered historical-figure guessing game developed and operated by Niobalan Network Technology (Shanghai) Co., Ltd. (“we”, “us”). You converse with AI historical figures whose identities are hidden, gather clues through questions, and guess who they are; guessing correctly unlocks the full figure archive.

1. Nature of AI-generated content: all character replies in the App are generated and portrayed by artificial intelligence models based on historical sources. They are educational and entertainment content, do not represent the actual words or positions of any real historical figure, and do not constitute any academic conclusion or professional advice. Generated content may contain factual errors, omissions, or inaccuracies; for historical details (lives, dates, events, quotations), always rely on authoritative sources. AI-generated content is identified as such within the App.
2. Acceptance: please read these Terms of Use (the “Terms”) and the Privacy Policy (together, the “Agreements”) presented at first launch. By tapping “Agree and Continue”, or by actually using the App, you confirm that you have read, understood, and accepted the Agreements in full. If you do not agree, please stop using and uninstall the App.
3. Reading guide: provisions that significantly affect your rights or obligations are shown in bold. Please pay particular attention to them before accepting. You may stop using the App at any time.
4. Eligibility: you must be a natural person with full legal capacity, or use the App under the guidance of a parent or guardian. You are responsible for ensuring that your use complies with all laws applicable to you, including those of your place of residence.

2. Accounts and Identity

1. Guest mode: you can experience the entire App as a guest, without signing in to any third-party account. A guest identity is bound to your device; if you reinstall the App or clear its local data before binding a sign-in method, guest progress may be lost and cannot be recovered. We may limit abnormal or high-frequency creation of guest identities to prevent abuse.
2. Sign in with Apple: the App's account sign-in method is Sign in with Apple. Authentication is performed by Apple; we never see, and have no need for, your Apple ID password. Apple's own account rules (for example, a revoked authorization) may affect your ability to use this sign-in method, and Apple's services are governed by Apple's own terms and privacy policy.
3. Guest upgrade and account switching (please read carefully):
   • If you first play as a guest and then sign in with Apple on the same device, your guest progress is carried into your account;
   • If you sign in to an existing account, the App switches to that account's data, and the guest progress from before sign-in does not merge into it;
   • PastEcho is operated as fully separate Chinese and international editions. Accounts, progress, and benefits are not shared or transferable between editions, even with the same Apple ID, and we provide no migration between them.
4. Account security: keep your device and Apple ID safe. All actions taken through your account (including conversations, consumption of benefits, and redemptions) are deemed your actions, and you bear their consequences. If your account is stolen or used abnormally, or you revoke Apple authorization in your device settings, please sign in again or contact us promptly.
5. Account deletion: you can delete your account yourself from within the App (guests may do the same; uninstalling alone only removes the local identity). The consequences and data handling are described in the Privacy Policy, Section 10 — account data is anonymized and cannot be restored. You acknowledge that deletion is your unilateral termination of these Terms and, once completed, is irrevocable.

3. User Conduct

When using the App you must comply with applicable laws and regulations and these Terms, and you must not:

1. create, copy, or distribute content that violates laws or public order and good morals, including content that is unlawful, infringing, harassing, discriminatory, defamatory, obscene, or that incites violence or hatred;
2. provide unlawful, infringing, harassing, or discriminatory content, or impersonate any person or organization (including us and our brands), in any input field such as nickname, avatar, chat, or feedback;
3. attempt to obtain or peek at other users' personal data, or harass or defraud other users;
4. harm us or third parties, including by reverse engineering or decompiling the App, scraping data, disrupting the normal operation of the service, or attacking our servers;
5. circumvent usage rules by any technical means, including mass creation of guest or registered accounts, fake invite attribution, simulating or forging ad plays to obtain rewards, or automated scripts that farm score and quotas;
6. use the App for commercial purposes beyond what these Terms allow, or seek unlawful gain through the App.

4. User Content and Content Moderation

1. User content: the chat text, guesses, nickname, avatar, and feedback you provide in the App (collectively, “User Content”) are created by you, and you are responsible for them. You warrant that your User Content is lawful and does not infringe any third party's intellectual property, portrait rights, reputation, privacy, or other rights.
2. Moderation: to meet content-safety obligations, we may (but are not obliged to) review User Content where necessary — in particular profile fields such as nickname and avatar, and feedback — and we build content-safety rules into the AI pipeline. For violating content we may, according to severity, refuse to store it, block it, hide it, or replace it with defaults; for violating accounts we may act under Section 4.3.
3. Enforcement ladder: if you breach these Terms or applicable law, we may unilaterally take one or more of the following measures, and will notify you in a reasonable manner except where the law provides otherwise:
   • warning with a deadline to correct;
   • deleting or blocking the violating content;
   • limiting features (such as pausing conversations);
   • clawing back benefits obtained through violation;
   • suspending or permanently banning the account.
   If your violation causes loss to us or a third party, you are liable for corresponding compensation; where a violation may constitute an offense, we will report to and cooperate with the competent authorities.
4. Reports: anyone who finds violating content or behavior in the App may report it through About → Feedback or the channels in Section 12; we will handle verified reports promptly.

5. Game Rules and Daily Limits

1. Core loop: pick a mysterious historical figure, gather clues through conversation, and guess the identity; a correct guess unlocks the figure archive, after which you may keep chatting as a friend and collect relics entrusted to you. Guesses are unlimited.
2. Daily puzzle: a featured figure rotates every day. The featured puzzle rolls over at 00:00 UTC; the App displays it together with your local time and countdown.
3. Daily limits and slots: to keep the service sustainable, daily usage rules apply. Under the current configuration, you can start up to 3 new-figure conversations per calendar day; each figure has a daily message quota, with a one-time bonus on the day you reveal that figure; when a quota or slot runs out you can watch a rewarded ad for a supplement (Section 6) or wait for the next reset. Your daily benefits reset according to your account's time zone. The exact numbers are as displayed in the App; we may adjust them from time to time and will announce changes in the App.
4. Score and progression: your guessing performance accumulates as Echo Score, together with titles, achievements, and relic collection. Echo Score is an honor-type score; see Section 6.3 for the nature of virtual benefits.
5. Sharing and invites: you can share conversation posters and reveal keepsakes through the system share sheet, and share links to the App. Shared items are generated on your device and may contain your nickname and chosen conversation content — please confirm the content is appropriate before sharing. When new users enter the App through your share links and meet the stated conditions, you may earn invite rewards (such as an extra new-figure slot) under the rules shown in the App; we may withhold rewards for abnormal or fake invite relationships.
6. Content risk notice: AI characters are portrayed from each figure's historical life, and their views are limited by their era and perspective; they do not represent ours. Where topics touch historical controversy, judge them against multiple sources and with reason. The App's content is not suitable as authority for teaching, examinations, or research.

6. Advertising and Virtual Benefits

1. Advertising: the App shows rewarded video ads provided by Google AdMob. Ads play only when you actively choose to watch them; after a full viewing you receive the stated benefit (such as extra daily messages, an extra new-figure slot, or unlocking a relic hint). Ads and their content are delivered by the third-party ad platform; we make no warranty about their accuracy or completeness. Any dispute between you and an advertiser arising from ad content or a transaction is between you and that advertiser, not us; you may take it up with the advertiser directly or complain to the relevant authority.
2. Viewing and reward rules: a reward normally requires watching the ad in full; closing early may forfeit it. Whether and how often ads are available depends on the ad platform's real-time inventory and controls, and no ad may be fillable at times — in that case you can continue through other means (such as waiting for the daily reset). Where rewards are obtained by fraudulent means (such as plugins or emulated plays), we may cancel the rewards and restrict the account.
3. Nature of Echo Score and virtual benefits: Echo Score, titles, achievements, daily message quotas, new-figure slots, relics, and similar items are virtual benefits attached to the Service. They have no property value, cannot be transferred or gifted, cannot be exchanged for cash or any physical goods, and are non-refundable. Except where the law provides otherwise, they expire without compensation when your account is deleted or the Service ends.
4. Rule adjustments: we may adjust ad formats, reward values, and frequency caps (such as daily viewing limits) for cost, compliance, or operational reasons. Adjustments will be announced in the App and do not affect honor-type records you have already earned.

7. Intellectual Property

1. Our rights: the App's software, interface and visual design, figure archive texts, historical-figure persona configurations, the clue and relic systems, badge and title systems, and similar content are owned by us or the relevant rightsholders, protected by copyright, trademark, and other rights. Without our written permission, no one may copy, adapt, distribute, or commercially exploit them, or use them to train competing models or for other competing purposes.
2. Your content: you own your User Content. To the extent needed to provide the Service (maintaining conversation continuity, content-safety review, generating shared items), you grant us a non-exclusive, royalty-free license, sublicensable to our service providers, to store, transmit, process, and display it. We will not use your content for other purposes or disclose it to third parties, except for providing the Service and lawful audits.
3. AI-generated content: AI replies you receive and shared items you generate are for your personal use and sharing; commercial use (including publication or sale) requires our prior written consent.
4. Third-party rights: names and marks of third parties appearing in connection with the App — such as Apple and Google — belong to their respective owners and may not be used by you without authorization. Image materials shown in the App are lawfully licensed or reasonably used where third-party rights are involved.
5. Notice and takedown: any rightsholder who believes content in the App infringes their rights may submit proof of ownership through the channels in Section 12; upon verification we will handle it promptly.

8. Disclaimers and Limitation of Liability

1. AI content disclaimer: AI-generated content comes from probabilistic models and may be wrong, incomplete, or inaccurate (Section 1.1). Do not treat AI replies as the sole basis for study, examinations, research, or writing. We are not liable for any direct or indirect loss arising from your reliance on or use of AI-generated content.
2. Availability: the App is provided “as is” and “as available”. We are not liable for interruptions, delays, or data damage caused by maintenance or upgrades, network failures, unavailability of third-party services (cloud hosting, databases, AI model providers, the ad platform, or Apple services), policy changes, or force majeure (natural disasters, epidemics, government actions, changes of law, and the like), although we will endeavor to repair or work around them.
3. Data risks: you understand that the internet is not absolutely secure. Despite the reasonable security measures described in the Privacy Policy, breaches or tampering cannot be ruled out entirely. Losses caused by your own acts (such as a lost device, lending your account, or disclosing information yourself) are borne by you.
4. Limitation of liability: to the maximum extent permitted by applicable law, our total liability to you (if any) is capped at the fees you actually paid to us for the App in the twelve (12) months preceding the event giving rise to liability. The App is currently free of charge, which means that within the limits allowed by law we bear no monetary liability. We are also not liable for indirect losses or lost expected benefits.

9. Changes, Suspension, and Termination

1. Service adjustments: we may add, adjust, suspend, or discontinue parts of the App as the product and operations evolve; for material changes that substantially affect your interests, we will notify you in advance through in-app announcements or similar means.
2. Termination for breach: if you breach these Terms or applicable law, we may suspend or terminate the Service to you under Section 4.3.
3. Your termination: you may stop using the App and delete your account at any time; these Terms then end for you, but Sections 6.3, 7, 8, 11, and 12 and any provisions that must survive by law remain effective.
4. Shutdown: if we decide to discontinue the App, we will notify you in advance as required by law and leave a reasonable period for you to export your honor records and complete account deletion, except where force majeure or regulatory requirements make advance notice impossible.

10. Notices

1. We deliver notices to you electronically, through in-app announcements and prompts; a notice is deemed delivered when it is sent (or displayed in the App).
2. Send any notice to us (including complaints, reports, and claims) through the channels in Section 12. Keep your contact information accurate; we are not responsible for failed replies caused by incorrect contact details you provide.
3. We fulfill our notice obligations in a reasonable and practicable manner; where the law mandates a specific form, that form prevails.

11. Governing Law and Dispute Resolution

1. These Terms are governed by the laws of the People's Republic of China (excluding the laws of Hong Kong, Macao, and Taiwan), without regard to conflict-of-laws rules.
2. Any dispute arising from these Terms or the App shall first be resolved through friendly negotiation; failing that, either party may bring a suit before the people's court of competent jurisdiction in Shanghai.
3. If any provision of these Terms is held invalid or unenforceable by a competent authority, the remaining provisions stay in effect, and the parties will replace the invalid provision with the valid provision closest to its intent.
4. Headings are for reading convenience only and do not affect interpretation.

12. Miscellaneous

1. Amendments: we may revise these Terms from time to time. For material changes affecting your major rights and obligations, we will notify you prominently in the App and seek your consent before they take effect. Continuing to use the App after a change takes effect means you accept the revised Terms; if you do not, stop using the App and delete your account. The version at the top of this page (“Last updated” and “Version”) identifies the current text.
2. Entire agreement: these Terms and the Privacy Policy together form the entire agreement between you and us regarding the App and supersede any prior oral or written understandings. Matters not covered here are governed by the Privacy Policy and applicable law.
3. No waiver: our failure or delay in exercising any right under these Terms is not a waiver of that right or of any later exercise.
4. Contact:
   • Operator: Niobalan Network Technology (Shanghai) Co., Ltd.
   • Email: support@neosura.com
   • In-app: About → Feedback