About blindfold-chess.app

🎮 User Guide

How to Play

This app is designed to be used eyes-closed and without using your voice. Simply put in earbuds, hold your device horizontally in your hands like a game controller, close your eyes, and control the pieces by just touching the screen-quadrants with your thumbs. The app offers a completely immersive, audio-guided blindfold chess environment.

Starting a New Game

1. Open the App: The app starts on the Menu screen.
2. Select Boards: Choose the number of simultaneous games you wish to play (from 1 to 64).
3. Choose Your Color: In case of playing one board: select "White" or "Black" from the "Choose color" dropdown. If you play multiple boards, there's an additional option where the color will alternate (White/Black) for each successive board.
4. Select a Bot: The bots are rated by their search depth (d#) and evaluation (cp). The easiest bot to defeat is "Benny (d1 / 500cp)". Benny thinks 1 half-move deep ("d1") and then evaluates the position. He often lets his pawns, knights and bishops be taken, sometimes even a rook (which is worth about 5 pawns, "500 centipawns"). Zola (d4 / 20cp) thinks at least 4 half-moves deep, at a good moment even 6 or 7. Lana (d15 / 20cp) is currently the strongest opponent, thinking at least 15 half-moves deep and playing extremely accurate.
5. Select Variant: Choose "Standard" for regular chess or "Chess 960" for a random starting position. The starting position will be displayed visually on the menu screen.
6. Intermediary Voice: The intermediary will tell you the moves that your opponent makes. If you choose voice A for the opponent's intermediary, your moves will be spoken by voice B, and vice versa.
7. Always Promote to Queen: By default, this option is enabled, meaning your pawns will automatically promote to a Queen. Uncheck this option if you want to manually choose your promotion piece (Queen, Rook, Bishop, or Knight) during the game.
8. Use physical buttons: Use this option if you're not using a touchscreen. A dialog opens to register 5 keys of your physical keyboard or 5 buttons of a game controller to simulate touchscreen taps.
9. Start Game: Tap the "Start Game" button to start playing.

When the game starts, the app will request to keep the screen awake (so that it doesn't lock or become inactive). When you close your eyes and start playing, this will ensure that the screen remains on and responsive to your touches.

Making a Move (Square Selection)

For a video explanation, see our YouTube short.

The game screen consists of four large, touchable quadrants:

• TL (Top Left)
• TR (Top Right)
• BL (Bottom Left)
• BR (Bottom Right)

When you use the app in full-screen mode, you can use your thumbs to tap these quadrants. To select any square of the 8x8 chessboard, you will make three consecutive taps on these quadrants. Each tap narrows down the selection to a smaller quadrant, eventually pinpointing a single square. Visual help is provided during play to get acquainted with this system.

Example 1: tapping BR BL TL selects E2 (for White)

• 1st tap, bottom-right: selects the bottom-right 4x4 quadrant (e1-h4).
• 2nd tap, bottom-left: selects the bottom-left 2x2 quadrant (e1-f2) within the previous 4x4 (e1-h4).
• 3rd tap, top-left: selects the top-left 1x1 square (e2) within the previous 2x2 (e1-f2).

Other examples:

TR TR TR selects h8 (or a1 if you have the black pieces):

TL BR BR selects d5 (or e4 if you have the black pieces):

Steps to Make a Move:

1. Select the "From" Square: Perform three taps to select the square of the piece you want to move.
   • The app will announce your chosen square (e.g., "Pawn from e2").
   • If the selected square does not contain one of your pieces, you will hear "Please select a valid starting square".
2. Select the "To" Square: Perform another three taps to select the destination square for your piece.
   • The app will announce the destination square (e.g., "to e4").
   • If the move is illegal, you will hear "That's not a legal move". The square selection is undone so that you can try again.

Promotion

If your pawn reaches the last rank and you have unchecked the "Always promote to queen" option in the menu:

1. After selecting the "to" square for your pawn's promotion, the app will announce: "Choose a promotion piece."
2. The four touchable quadrants will now display the promotion options:
   • Top Left: Queen
   • Top Right: Rook
   • Bottom Left: Bishop
   • Bottom Right: Knight
3. Tap the quadrant corresponding to the piece you wish to promote to.
   • The app will confirm your choice by finishing the move sentence with – for example – "promoted to Queen". The full sentence that you've heard, might then be: "Pawn from f7 takes g8 – choose a promotion piece – promoted to Queen".

Using the Game Menu

During a game, tapping the white square in the center will open a menu with the following options:

• "Undo Last Move": Tap this to undo the last full move (your move and the AI's response). In multi-board mode, it will undo the current board's last (AI) move and then switch to the previous board to undo your last move.
• "Cancel Selection": If you've started selecting a square but want to reset, tap this button. It will clear your current partial selection. A shortcut for this (without opening the game menu, keeping your eyes closed) is to swipe from right to left over at least 25% of the screen width.
• "View PGN": When in doubt about the move history, you can see the history of all the boards you're playing in a PGN-like format and then "Resume Game".
• "Main Menu": Returns you to the main menu. Here you can review the 960 starting position and then click "Resume Game".
• "Resume Game": Returns you to your current game.

Tips for Beginners

• Make sure you don't get disturbed: Choose a place and a time to practise so that nobody interrupts your training session.
• Start simple: Begin with standard chess, 1 board, bot "Benny (d1 / 500cp)".
• Trade pieces: Do many exchanges to clean the board, making it easier to remember.
• Verify that you remember: During each of your turns (or maybe less), try to remember all piece positions. This costs time, but trains your brain. How many moves did you do without loosing track? Play more slowly next time: verify/remember more often. Later you will not need to do this so consciously anymore.
• Stop the game when you forgot a piece position: When in doubt about a piece position, use the "View PGN" button. After analyzing (without a board), stop your training session.
• Don't expect quick results: Start only one game per day. Trust that your brain changes itself during sleep. After a few days of practice (one game start per day), you might notice that you're able do more moves before forgetting the current position or making a blunder.

Next Level Tips

• Go 960: To avoid playing openings from memory, play 960 as soon as you have defeated the first opponent. Memorize only the file names of the bishops, queen and knights (for example "EF, A, DG") and then press "Start Game". Rehearse the starting position a few times from left to right and from right to left before starting to think about your moves.
• Don't be scared of 2 boards: When you feel comfortable with 1 board, add a second board. It may seem daunting, but it may actually not be a big step after you've mastered playing 1 board blindfolded.
• Take care of your health: Some professional players advise against playing too many boards blindfolded. Take care of your brain ❤️

Live streaming a game

If you are a chess streamer / content creator, feel free to use our live stream feature. Here are the steps to play on your phone and have a boards viewer on your computer:

1. On your phone, open the app. Press the title "blindfold-chess.app" three times.
2. Below the "Start Game" button, you can now see a "STREAM ID".
3. On your computer, open blindfold-chess.app/live, fill in the ID and press play.
4. On your phone, press "Start Game".
5. Your (simul) game is streamed live now! Video-record the page blindfold-chess.app/live for your viewers while you play on your phone eyes-closed/blindfolded.
6. When the game is finished (on all boards), buttons will appear at blindfold-chess.app/live for reviewing the moves with your viewers.
7. To stop streaming, go to the main menu in the app on your phone and press the title "blindfold-chess.app" another three times. Your phone then stops pushing moves to the "/live" page.

Notes: the "/live" page is not meant for direct use by your viewers. You should share a video-stream of that page to your viewers.

Frequently asked questions

Is this app free?

Yes, the License Agreement of blindfold-chess.app may be summarized as "free to use, not to copy". You can use this app for free, including if you're taking part in professional chess activities such as tournament play, coaching, or content creation (that give you income). You can upload videos or stream your games live using this app, as long as the URL "blindfold-chess.app" is visible for at least a few seconds.
However, you may not copy, reproduce, distribute, modify, create derivative works of the app, including its code, design, or unique features. If you are sharing ideas from this app with others, please also refer them to blindfold-chess.app directly.
The idea of the touch-based input system, with 3 taps to select a square, is unique – a proprietary feature found exclusively on blindfold-chess.app and owned by Symbolinker (symbolinker@gmail.com). Licenses are available if you're interested in using this idea, or parts of this app, in your own application/website/etc. For more information, see the License Agreement section or visit blindfold-chess.app/partners.

Can I download the app?

Yes. This app is a Progressive Web App (PWA) and can be installed on your device. When you open the app in a browser and see "blindfold-chess.app" in the URL bar, then, depending on your browser (e.g. Chrome, Edge, etc.), you might see, near the URL bar or via the browser menu, an icon for installing this app on your device*. After installing, the app will appear on your home screen, and you can launch it from there. If clicking on the app icon opens a regular browser tab, then only a shortcut has been placed on your home screen. Try installing the app via a different browser.

* On iPhone in Safari, tap the Share button (the square with an up arrow), select "Add to Home Screen".

Can I use this app offline?

Yes. There are two options:

1. Install the app (see above) and turn off your internet connection.
2. Use the app in a browser without installing it. This web app asks your browser to cache the whole app, so that when you loose your internet connection or play offline deliberately, the app still works.

How to enter fullscreen mode?

Playing the app in fullscreen mode prevents that you touch outside of the game screen of the app. Using the app eyes-closed, you don't want to accidentally close the app or click on the URL bar while thinking that you are selecting a square!

The app requests your browser to enter fullscreen mode when clicking "Start Game". However, this may not work on all devices or browsers. If it doesn't, you can try the following:

• When installed on Android, the app opens fullscreen automatically.
• On iPhone in Safari, tap the Share button (the square with an up arrow), select "Add to Home Screen" and launch it from there.
• On Windows, press F11 (or fn + F11).
• On Mac, press Control + Command + F (or Fn + F).

If your device does not support a fullscreen mode, then you can use a workaround: make a cardboard box around your screen with a rectangular hole for the game screen - cardboard can cover the device's/browser's navigation controls that might close the app.

Can I play against a human opponent?

No, not yet. You can ask your favorite chess website to become a partner. Then you might play blindfolded against a member who doesn't play blindfolded, or create a game that requires the other member to also play blindfolded.

Other questions?

For other questions, requests for improvements or partnering, feel free to e-mail to symbolinker@gmail.com.

📚 License Agreement

Last updated: 28-08-2025.

This License Agreement (the "Agreement") governs your use of the Blindfold Chess App (the "App"), located at https://blindfold-chess.app, and its associated features and intellectual property. By accessing or using the App, you agree to the terms of this Agreement.

Central to the App is a proprietary method for selecting an item from a grid, hereinafter referred to as the "Input System". For the purposes of this Agreement, the Input System is defined as:

A method for selecting a single square from an 8x8 grid through a sequence of three user inputs. The method is based on a hierarchical decomposition of the grid:

1. The 8x8 grid is first divided into four 4x4 quadrants. The first user input selects one of these four quadrants.
2. The selected 4x4 quadrant is subsequently divided into four 2x2 sub-quadrants. The second user input selects one of these four sub-quadrants.
3. The selected 2x2 sub-quadrant contains four individual squares. The third user input selects one square from these four.

This Input System is independent of the input mechanism (which may include, but is not limited to, screen taps, button presses, swipes, or joystick movements) and the visual representation of the grid.

1. Ownership and Copyright

The App, including its Input System and overall design, is the proprietary intellectual property of Symbolinker (symbolinker@gmail.com) and is protected by copyright laws. All rights not expressly granted to you in this Agreement are reserved by Symbolinker.

2. Permitted Uses

2.1. Free Individual and Personal Use

You are granted a free, non-exclusive, non-transferable license to use the App for your individual and personal purposes. This includes, but is not limited to, practicing, training, and improving your blindfold chess skills. This permission extends to individuals who may earn income from professional chess activities, such as tournament play, coaching, or content creation, provided their use of the App itself remains personal and does not involve the commercial reproduction, distribution, or integration of the App's unique features into other commercial products or services.

2.2. Educational and Content Creation Use

Chess teachers, online content creators, and similar educational entities are permitted to use and showcase the App for instructional or demonstration purposes, including playing games. When doing so, the URL "blindfold-chess.app" must be visibly displayed for at least a few seconds in any content created (videos, streams, screenshots, etc.).

3. Restricted Uses

Unless explicitly granted through a separate commercial license agreement with Symbolinker, the following uses are strictly prohibited:

• Commercial Use: Any use of the App or its unique features for direct or indirect commercial gain, including but not limited to selling access to the App, incorporating it into a paid product or service, or using it for advertising purposes.
• Reproduction and Distribution: Copying, reproducing, distributing, modifying, creating derivative works of, publicly displaying, or publicly performing any part of the App, including its code, design, or unique features, outside of the blindfold-chess.app domain.
• Reverse Engineering: Attempting to decompile, reverse engineer, disassemble, or otherwise discover the source code or underlying algorithms of the App.
• Sub-licensing: Granting sub-licenses to others to use the App or any of its components.
• Use in Other Applications/Websites: Integrating the Input System or any other proprietary elements of the App into other applications, websites, or platforms without a specific license.

4. Commercial Licensing

For any use beyond the "Permitted Uses" described in Section 2, particularly for commercial purposes or integration into other applications/websites, a separate commercial license is required. Please contact Symbolinker at symbolinker@gmail.com to inquire about licensing opportunities or visit blindfold-chess.app/partners.

5. Third-Party Licenses

The App incorporates third-party software components, each governed by their respective licenses:

• Stockfish.js: Used for the AI opponent. Its license can be found at the official Stockfish repository.
• Chess.js: Used for chess logic. Its license can be found at the chess.js repository.
• Chessboard.js: Used on the live stream page. Its license can be found at the chessboard.js repository.

Your use of the App acknowledges and abides by these third-party licenses where applicable.

6. Disclaimer of Warranties

The App is provided "as is," without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose, and non-infringement. In no event shall Symbolinker be liable for any claim, damages, or other liability arising from your use of the App.

7. Governing Law

This Agreement shall be governed by and construed in accordance with the laws of The Netherlands, without regard to its conflict of law principles.

8. Changes to This Agreement

Symbolinker reserves the right to modify this Agreement at any time. Your continued use of the App after any such modifications constitutes your acceptance of the new terms.

For any questions regarding this License Agreement, please contact Symbolinker at symbolinker@gmail.com.

🛡️ Privacy Policy

Last updated: 26-10-2025.

We are committed to collecting as little data as possible. This Privacy Policy describes why, what, and how we collect and use data from users of the blindfold-chess.app.

Offline mode

If you use the app without an internet connection, we do not collect any data about you or your usage. The app will not send information about previous usage when you later connect to the internet. You can play games completely offline and anonymously.

Online mode

When your device is connected to the internet, the app sends logging for two purposes:

• to find and fix technical problems for specific devices.
• to get an idea of how many people are using the app and how often certain features are used.

The logging includes these components:

• App ID: A random, anonymous ID is generated once by the app and sent with each log event. This allows us to group log events without identifying you personally.
• Technical Data: The app's version, your device's operating system and its version (e.g. "Android 10" or "iPhone OS 17").
• Event information: At the beginning of a game, we log the settings (e.g. number of boards, game variant, difficulty level, color, value of "Always promote to queen", physical button mapping if used, intermediary voice setting). At the "first move done", we log that a first move was made, but not which move it was. At an error, we log the error message. We log whether a game was finished, but we do not log your moves or the game result (win/draw/loss). If you use the "Share" button in the PGN viewer, we log that you used it, but we do not log the content of what you shared. We do not log the usage of the "Undo Last Move" button. We tested it in many scenarios and really want the "Undo Last Move" button to be private, not even logged anonymously.

Here is an example of logging:

The data we collect is not shared with any third parties for marketing or other commercial purposes. However, we use a service provided by Google to directly receive, process (using Google Apps Script) and store the logging data (in our Google Drive account). Google might, when its Apps Script service receives the logging data, collect data that is a standard part of all internet requests, such as the User Agent (e.g., Mozilla/5.0...), the request timestamp, and the sender's IP address. We do not collect IP addresses.

Updates and questions

We may update this Privacy Policy from time to time, so we encourage you to review it periodically.

For any questions regarding this Privacy Policy, please contact Symbolinker at symbolinker@gmail.com.