Privacy Policy

Last updated: 10 August 2026

This policy covers Sudoku Classic: Legacy Puzzle — the browser version at sudokulegacy.com, and the Android and iOS builds of the same game — and this website. It is written against what the software actually does; where a third party is involved, it is named.

1. Who we are

PVH Game Studio is a trading name rather than a registered company: the game and this website are made and published by an independent developer based in Vietnam, working as an individual.

There is no company behind the name, no business registration number, and no registered office. Where this policy says "we" or "us", it means that one developer. Questions about anything on this page go to [email protected].

2. Where the game is available

The game is not published or distributed in Vietnam.

Offering a game to players in Vietnam requires a licence that is granted to registered companies, and PVH Game Studio is an independent developer working as an individual rather than a company, so no such licence is held. The game is therefore not offered, published, advertised or distributed to players in Vietnam, and it does not ship a Vietnamese-language interface.

This is a question of licensing rather than of where the work is done: the developer is based in Vietnam, while the game is published only in the other countries the app stores reach. See the terms of use for the same statement in full.

The restriction is applied to this website by checking which country a request arrives from. That check uses your network address and is described in section 5 — it is the one thing on this site that looks at where you are, and it does nothing else with the answer. This policy and the terms of use stay readable everywhere, including from Vietnam, because they are where this is explained.

3. What the game stores, and where

Everything the game remembers is written to storage that belongs to your own device — your browser's localStorage on the web, and the platform's standard app preferences on Android and iOS. None of it reaches us, because there is nowhere for it to go: the game makes no request to any server of ours at any point.

• The puzzle you are part-way through — the clues, your entries, your pencil marks, the clock and your mistake count — saved after every move so Continue works.
• Your best time for each difficulty.
• Your statistics: games started, games won, average times and streaks, per difficulty.
• Your Daily Challenge history and current streak.
• Your settings: language, colour theme, sound, music, haptics, and whether you have already seen the how-to-play screen.
• On mobile only: if you choose a photo as the board background, a copy of that one image inside the app's own private folder.

Because there is no account, none of this syncs between devices, and none of it is backed up anywhere by us. Clearing this site's data in your browser, or uninstalling the app, removes all of it.

4. Puzzles are generated on your device

Every grid — Classic and Daily Challenge alike — is generated by the game itself, in your browser or on your phone. Nothing is downloaded, so nothing about which puzzle you played, how long you took, or how many mistakes you made ever leaves the device. The Daily Challenge is the same for everyone on a given date because it is seeded from the date, not because a server handed it out.

5. This website

Cookies

This site sets no advertising cookies and no preference cookies. Two cookies can be set, and this is the whole list:

• _ga and _ga_<id> — set by Google Analytics, and only once you have agreed to it where we ask; see the next section for where that is. They are first-party cookies holding a randomly generated number that tells one browser apart from another. They carry no name, no address and nothing you typed, and they last two years unless you clear them.
• A short-lived Cloudflare cookie, set only on a request Cloudflare has to challenge, so it can remember the challenge was passed. It is a security measure and carries no advertising or analytics purpose. It is not ours to remove.

Your answer to the banner is remembered in your browser's localStorage, not in a cookie — declining should not itself store the kind of thing you just declined.

Analytics

This site uses Google Analytics 4 to count visits — how many people arrive, which pages they read, how they got here, and roughly where in the world they are. It is there to tell whether writing a rules page was worth doing, not to follow anybody.

Whichever applies to you, Cookie settings in the footer reopens that choice at any time, and changing your mind takes exactly as many clicks as making it up did.

What Google receives on each page view: the address and title of the page, the page you came from, your browser, operating system, device type, screen size and language, an approximate location worked out from your network address, and the random identifier in the _ga cookie. Google states that it uses the network address to derive that approximate location and does not log or store the address itself in Analytics.

What it does not get: any name, email address or account, because there is no account anywhere in this product. And nothing about your game — which puzzle you are on, your times, your statistics and your settings never leave your device, as section 3 describes. Analytics measures pages, not play.

Where it runs: the website only, which includes the /play page, because that page is part of this site. The Android and iOS builds contain no analytics code at all — see section 8.

Google's handling of what it receives is described in Google's privacy policy and in Google's note on Analytics and data. Besides the banner you can block cookies for this site in your browser, use Google's own opt-out add-on, or use any content blocker — none of which affects the game, which needs no network at all once the page has loaded.

Where you are connecting from

The game is not offered in every territory — section 2 explains which and why — and that restriction has to be applied somewhere. This site is served through Cloudflare, a content delivery and security provider that sits in front of the server. Cloudflare determines a two-letter country code from the network address your request arrives with, and passes that code to the server, which uses it for one purpose: to decide whether to serve the game or the page explaining that it is unavailable.

Two things this is not. It is not an attempt to locate you precisely — a country code derived from a network address says nothing finer than a country, and is frequently wrong about even that. And it is not retained: the code is read from the request, used to choose which page to send, and discarded with the request. It is not written to a profile, not attached to anything else about you, and not used for advertising or analytics.

Your network address itself is processed by Cloudflare in the ordinary course of delivering and protecting the site, under Cloudflare's privacy policy, and appears in this server's access logs as described just below.

Browser storage

The /play page stores your game, statistics and settings in your browser's localStorage, as described in section 3. That is strictly necessary for the feature you asked for — a game that remembers where you were — and it is readable only by this site, only on this device.

Server logs

Like any web server, this one writes access logs: IP address, browser and operating system, timestamp, the page requested and the referring page. They exist to keep the site running and secure, not to build a profile, and they are not combined with anything else.

Error monitoring

The server uses Sentry to report its own errors. When a request fails, Sentry receives technical details of that failure — the error, the stack trace, the URL, and the environment the server is running in. It is a server-side integration: no Sentry code runs in your browser, and no script from Sentry is loaded by any page here. Sentry's handling of the data it receives is described in Sentry's privacy policy.

Third-party requests

Every asset this site needs — the stylesheet, the fonts, the images, and the whole game bundle including its rendering engine — is served from this domain. Cloudflare is not an exception: your browser connects to this domain and Cloudflare answers for it, so nothing is fetched from anywhere else.

Two requests may go elsewhere. The first is on every page, and only once analytics is on: the Google Analytics tag is loaded from googletagmanager.com and sends its measurements to google-analytics.com. Where the banner asks first, neither host is contacted at all until you agree — the script is not on the page, so there is nothing to block.

The second is on /play only. The engine the game is built with fetches its own default typeface from Google Fonts (fonts.gstatic.com) when it starts, and would fetch a fallback face from the same place if a page ever needed a character the bundled fonts do not cover. That request carries your IP address and the usual headers a browser sends, and it is cached by your browser afterwards. It is part of how the engine works rather than something we added. Google describes what it does with Google Fonts requests in its Google Fonts privacy FAQ.

6. Advertising in the mobile apps

The browser version shows no advertising and contains no advertising code.

The Android and iOS builds include the Google Mobile Ads (AdMob) SDK and display a banner at the bottom of the game screen. To select and measure those ads, Google may collect information such as your device's advertising identifier, IP address, device model and general location. That happens inside Google's SDK; we do not receive that data and cannot identify you from it.

Google's handling of it is described in Google's advertising policy and Google's privacy policy. You control it at the operating-system level:

• Android: Settings → Google → Ads, where you can reset or delete your advertising ID.
• iOS: Settings → Privacy & Security → Tracking, and the permission prompt the system shows.

7. Photos (mobile only)

On Android and iOS you may set one of your own photos as the board background. Doing so opens the system photo picker and asks it for a single image. The app copies that one image into its own private storage — so it survives the picker's temporary permission — and does nothing else with it. It is never uploaded, and the app does not read your photo library beyond the image you pick. Removing the background deletes the copy.

The browser version has no such feature, and does not ask for access to any files.

8. Permissions and third-party code

The complete list of third-party components in the software, and why each one is there:

Inside the game itself there is no analytics SDK, no crash-reporting SDK, no Firebase, no in-app purchase, no push notifications, no Google Play Games and no Apple Game Center. That is true on every platform including the web: the analytics in the row above is a tag on the website's pages, not code in the game. The Android app requests internet access only because the advertising SDK requires it; the game does not use it.

9. What we do not do

• No account, no email address, no sign-in with Google, Apple or anyone else.
• No analytics or tracking code inside the game, on any platform. The website counts page visits — section 5 says exactly what that involves — and it measures pages, never play.
• No selling or sharing of personal information — we hold none to sell.
• No access to contacts, microphone, camera, precise location or files, beyond the one photo you may pick yourself on mobile. The country check in section 5 is not location access: it reads a country code from your network address and nothing finer.
• No advertising scripts and no advertising cookies on this website. The only cookies it sets are the two analytics ones in section 5 — after you have agreed, where we ask — plus the security one Cloudflare may set on a challenged request.
• No consent banner that only takes yes for an answer. Both buttons are the same size, "No thanks" is one click, and Cookie settings in the footer takes the answer back just as easily.

10. Children

This is a Sudoku game suitable for a general audience, and it does not knowingly collect personal information from children. If you believe a child has provided personal information through something we operate, write to the support address and we will remove it.

11. Your data and your rights

Because everything the game records stays on your device, you already hold all of it. There is no server-side copy for us to delete and no export for us to send you. To erase it, see Your Data for the exact steps on each platform.

If you are in a jurisdiction that grants rights of access, correction, erasure, portability or objection over personal data, those rights apply to whatever a controller actually holds — which here is server access logs and error reports, and nothing else. Write to the support address to exercise them.

12. Where data is processed

The developer is based in Vietnam, and this website is hosted on a server rented from an infrastructure provider. The third parties named above — Google, for analytics on this website, for advertising in the mobile builds and for the font the web engine fetches; Sentry, for server error reports; and Cloudflare, which every request to this site passes through and which sees the network address it came from — operate internationally and process what they receive on their own infrastructure, under their own policies. Google Analytics in particular processes what it receives on Google's own infrastructure, which means outside the country most readers are in.

Everything the game itself records never moves at all: it is written to your device and stays there.

13. Changes to this policy

If the software starts doing something this page does not describe, this page changes first, and the date at the top changes with it.

14. Contact

Questions about this policy: [email protected].

About the studio: About Us · Contact Us.