Privacy Policy

1. The short version

Làng Game Việt lets you play traditional Vietnamese games with the people sitting next to you: Ô ăn quan (mancala), Cờ caro (gomoku), Cờ gánh, Cá ngựa (ludo), Tam cúc (a folk card game), Tiến lên (a shedding game on a 52-card deck) and Cờ tướng (xiangqi). To play together, the devices must be on the same Wi-Fi network. One device hosts the room; the others connect straight to it.

We run no servers. There are no accounts, no sign-in, no ads, no in-app purchases, no analytics, and no trackers of any kind inside the app. Your game travels from one device to another inside your own home network and stops there — it does not pass through us, because there is nothing of ours for it to pass through.

In app-store language: we do not collect user data. But "we collect nothing" is not the same as "nothing happens on your device", so the rest of this document spells out exactly what does.

2. Who is responsible

The app is published by Nguyen Pham. For any privacy question, write to [email protected]. We aim to answer within 30 days.

3. What we do NOT do

The short list, so you don't have to read further:

• No cloud server, no database, no API on our side. Your game travels only to the room host you choose on your local network; nothing reaches us, because there is nothing of ours for it to reach.
• There is one exception we want to state plainly, and it exists only on Android: the QR scanning feature uses Google's ML Kit barcode scanner. The recognition model is bundled inside the app, so camera images never leave your device — but that component pulls in parts of Google Play Services and Firebase, and those parts may send diagnostic data to Google in ways we do not control. The iOS build contains no Google components at all; it uses Apple's built-in Vision framework instead.
• No accounts, no sign-in, no passwords, no social login.
• We do not collect your real name, email, phone number, address, date of birth, gender or any other personal information. The app has nowhere for you to type any of that.
• We do not read your contacts, photos, files, calendar, messages, microphone, health data or GPS location.
• No ads, no ad networks, no use of the device advertising identifier (IDFA / Advertising ID).
• No analytics SDK (no Firebase Analytics, Google Analytics, Facebook SDK, AppsFlyer, Adjust — none of them).
• No crash-reporting SDK (no Crashlytics, no Sentry). If the app crashes, we do not find out unless you write and tell us.
• No in-app purchases, no subscriptions, no payments, no virtual currency, no gambling. Tam cúc and Tiến lên in this app are card games played for fun; the score lives inside the round and has nothing to do with money. Tiến lên does score the traditional end-of-hand penalties ("thối heo" and "cóng"), but they are penalty points in the game's own unit — the same scale as the cards left in your hand — not stakes: nothing is put up before a hand, and the number disappears with the room.
• No chat box, no comments, no outbound web links, no content uploaded by strangers.
• We do not sell, rent or share your data with anyone — there is no data on our side to sell.

4. What ACTUALLY happens while you play

This is the important part. We list every item, including the small ones.

4.1. The nickname you choose

The first time you open the app, the device gives you a playful nickname (things like "Mèo Lém", "Cò Nhanh"). Tap it to change it to anything you like, up to 20 characters. This nickname is:

• stored on your device, so you don't have to type it again next time;
• sent to the other devices in the same room — that is what playing together means; without a name nobody can tell whose turn it is;
• visible on the Wi-Fi network while you host a room, see section 4.3.

Because you type the nickname yourself, you decide entirely what it says about you. We recommend a nickname rather than your full legal name, especially on a child's device. You can change it at any time from the home screen.

4.2. A randomly generated player code stored on the device

The first time you open the app, the device generates a random 16-character string (something like k3f9a2m0z1x7c5b8) and stores it locally. It serves one purpose: recognising that you are "the same person as a moment ago" when your connection drops mid-game, so you get your original seat back instead of being treated as a newcomer and turned away because the room is full.

About that string:

• It is not the device advertising identifier, not an IMEI, not any identifier issued by the operating system. The app picks it at random and reads nothing from your device.
• It is not linked to any account, email, phone number or real name.
• It is sent only to the room host you deliberately join, during the join handshake. It goes nowhere else.
• Uninstalling the app removes it from the device. Reinstalling generates a completely new one, with no way to link it to the old one — with one exception: if device backup is switched on, the old string may sit in your own iCloud or Google backup and come back with a restore. See section 5.

We never receive this string, we store it nowhere except on your device, and we do not use it to track anything.

4.3. Local IP address and room name on your home network

When you tap Create room, the app opens a network port on your device and advertises a small record on the current Wi-Fi network so your friends can find it. That record contains:

• the room name — by default "Phòng của <your nickname>" ("<your nickname>'s room");
• the network port in use (a random port assigned by the operating system);
• the game code being played and the protocol version number.

Alongside it, the operating system itself advertises your local IP address (such as 192.168.1.7) and your device name (such as iPhone-cua-Binh.local). The device name is set by the operating system and the app does not change it. The local IP address, however, the app does read — it asks the operating system for the device's IPv4 address and shows it on the room screen, so anyone who cannot scan the QR code can type that address in by hand. Showing it on screen is where it ends: the app neither stores it nor sends it anywhere.

This means: while a room is open, every device on the same Wi-Fi can see the room name — and therefore the nickname you chose — including people who never join the game. This is the only way "find rooms nearby" can work. Closing the room stops the advertisement immediately.

This local IP address belongs to your home network, is not your public IP address, and is only visible from inside that network. It never reaches the internet and we never see it.

When you join someone else's room, your device is visible to the host in the way any network connection is visible: local IP address and port. Plus the nickname and player code described above.

4.4. The QR code

The host can display a QR code so friends can join quickly. It contains the local IP address, port, room name and game code — exactly what is already advertised on the Wi-Fi, nothing more. If the room name contains your real name, don't post a screenshot of that QR code on social media; even so, the address inside it is only usable by someone already on your home network.

4.5. Camera

The app asks for camera permission only to scan a room's QR code. The camera turns on only when you open the scanner screen yourself, and turns off as soon as you leave it.

• The app takes no pictures, records no video and saves no frames.
• Camera images are never transmitted anywhere. Decoding happens on the device; the only thing the app extracts is the text inside the code.
• If you deny camera permission, the app still works: the scanner screen explains why and offers a button to type the room address by hand, and discovering nearby rooms still works. (Both run over the local network, so on iPhone/iPad they still need the Local Network permission described in section 6.)

4.6. Sound

The app has a mute button, and remembers your choice on the device. The app only plays sound from files bundled inside it; it never records sound and never asks for microphone permission.

4.7. Playing solo against the computer

If you choose "Play against the computer", no networking happens at all. No port is opened, nothing is advertised on the Wi-Fi, no connection is made. The computer works out its moves on your own device.

4.8. Game content

Game state — the board, the cards, the dice, the score — travels only between the devices in the room. Games are not recorded: closing the app discards the state, the app keeps no match history, no leaderboard, and writes no log files to your device.

One small thing, for completeness: while running, the app prints a few technical lines to the operating system's own log (things like "listening on 192.168.1.7:52345") to help with debugging. Those lines are not written to any file of the app's, are never sent anywhere, and stay in your device's system log, handled by the operating system.

For Tam cúc and Tiến lên specifically, the host filters the state before sending it to each player: other players' hands never travel over the wire at all, rather than being sent to everyone and merely hidden in the interface. The number of cards each player still holds is sent, because anyone at the table can count that anyway.

5. Data stored on your device

The app stores exactly four items, using the operating system's standard settings store (shared_preferences, which is UserDefaults on iOS/macOS and SharedPreferences on Android). All four live in the app's private area on your device, and none of them ever reaches us or any third party — we have no server to receive them. Two of the four do travel to the devices of the people you play with when you join a room; the last column of the table says which.

Nothing else is written to your device.

About device backups. That settings store is included in the device backup by default — iCloud or a computer backup on iPhone, Google backup on Android. So your nickname, player code and sound setting may travel into your own iCloud or Google account backup and come back when you switch phones or reinstall the app. That is between you, Apple and Google, under their backup policies; we neither touch it nor see it. If you would rather it did not happen, turn backup off for this app in your device's backup settings.

6. Permissions the app requests, and why

On iPhone / iPad

The app declares a Bonjour service named _langviet._tcp — a dedicated channel for finding this app's own rooms, not a way to look around at other devices in your home.

On Android

7. Third-party libraries

The app uses a few open-source libraries for technical work. None of them sends your game data or personal information anywhere, and none of them is an advertising or behavioural analytics SDK. The one exception regarding outbound traffic is stated in section 3 and repeated in the last row of the table:

We deliberately generate the sounds with a script and draw the interface ourselves rather than fetching content from a remote server, so the app works completely offline.

8. Security — stated plainly

Traffic between devices during a game is plain JSON over TCP, not encrypted. This is a deliberate choice: the app runs inside your home network, needs no certificates, needs no server, and works the moment it is installed.

That means anyone with privileged access to that Wi-Fi network — a network administrator, or someone capable of capturing packets — could in principle read nicknames and game moves. A game of mancala is hardly a secret, but you should know this in advance. So:

• Don't put anything into your nickname that you wouldn't want read.
• If it concerns you, play only on your own home Wi-Fi or your own hotspot, not on café or public Wi-Fi.

On the other hand, because the data never leaves your local network and no server of ours holds it, the familiar risk of "company leaks its user database" does not apply here — we have no database to leak.

9. Children

The app is made for families to play together. It contains no violence, no gambling for money, and no adult content. There are no ads, no in-app purchases, no chat box, no outbound web links, and no content uploaded by strangers.

Because the app collects no data from anyone, no children's data is collected either — including from children under 13 (COPPA, United States), children below whatever age each EU member state sets under the GDPR (between 13 and 16), or children under 16 under Vietnam's Law on Children and Decree 13/2023/ND-CP.

The only place a child types free text is the nickname field. Parents should encourage a nickname rather than a real full name, because that name is visible to devices on the same Wi-Fi (section 4.3). An adult can change it back at any time.

If you believe your child has provided personal information to us, please write to [email protected]. In practice we receive nothing: there is no path for data to travel from your child's device to us.

10. Your rights, and how to delete your data

Laws in many places — Vietnam's Decree 13/2023/ND-CP, the EU GDPR, California's CCPA/CPRA — give you the right to know, to access, to correct, to delete, to port your data, to object to processing, and not to have your data sold.

We respect all of those rights. The one wrinkle is that we hold no data about you, so there is nothing for us to export, correct or delete on request. In GDPR terms: since no data ever reaches us, we are not a data controller for any data of yours. Everything lives on your device, and you can act on it yourself right now:

• Change your nickname: tap your name on the home screen, type a new one, save.
• Delete everything the app stored: uninstall the app. Both iOS and Android remove the app's stored data from the device with it. If device backup is on, those four items may still sit in your iCloud or Google backup and return on reinstall — to be rid of them entirely, turn backup off for this app before uninstalling (section 5).
• Delete without uninstalling (Android): Settings → Apps → Làng Game Việt → Storage → Clear data.
• Delete without uninstalling (iOS): iOS does not offer per-app data clearing, so the only way is to delete and reinstall the app. After reinstalling, the app treats you as an entirely new person — unless an iCloud backup restores the old settings, see section 5.
• Revoke camera or local network permission: device Settings → Làng Game Việt → turn the relevant permission off.

If you would still like to submit a formal privacy request, write to [email protected]; we will answer within 30 days, even if the answer is "we hold nothing of yours".

11. How long data is kept

• The four items in section 5: on your device until you delete them or uninstall the app; if device backup is on, they also sit in your own iCloud or Google backup for as long as Apple or Google keeps it.
• Game state: only in memory while the app is running; gone when you close it.
• On our side: nothing, so there is no retention period.

12. International data transfers

None. The data never leaves your local network, so it never crosses a border.

13. Changes to this policy

If a future feature changes anything described above, we will update this document and record the update date at the top. For any significant change, the release notes of that update will say so before the feature reaches you. The current version always lives at https://app.359258.net/LangGameViet/privacy-policy.html.

14. Contact

Nguyen Pham Email: [email protected]