Chess

A fully offline chess app for your phone, with an 8-bit look. Stockfish 19 runs on the device (WebAssembly), so there is no server, no account and no signal needed.

Features

Play

• Eight opponents, each unlocked by beating the one before. Strength runs from The Tourist (~800) through The Visitor (1320), The Docent (1500), The Guide (1700), The Archivist (1900), The Curator (2200) and The Director (2600) to full-strength Stockfish (3190).
• Pass and play with a friend on the same phone.
• Choose White, Black or random.
• Tap a piece then a square, or drag it. Legal moves are highlighted, and pawn promotion asks what you want.
• Hint shows the engine's best move with an arrow. Undo, Flip the board and Resign are always there.
• Resume an unfinished game after closing the app.
• Optional eval gauge, a thin bar beside the board. Leave it off to train your eye.
• An "unlock every opponent" switch skips the ladder.

Games

• Every game is saved on the device, with result, opponent and move count. Delete any of them.
• Import Lichess or Chess.com games by pasting a PGN. Copy PGN and Copy all games export them.
• Step through any game with the move list.

Analyze

• Tap Analyze and Stockfish checks every move of a finished game.
• You get an accuracy score, an eval graph and every move labelled as an inaccuracy, mistake or blunder.
• Arrows on the board show your move against the engine's choice.
• Copy for Claude copies the position and a question so you can ask an AI why a move was bad.

Puzzles

• Your own blunders and mistakes become puzzles: the position from your game, where a better move existed.
• Find the best move. Wrong answers can retry, Reveal shows the answer and Skip moves on.
• Tracks your streak, best streak and solved count. A position is mastered after two correct solves.

Look and feel

• Pixel-art pieces: a black set and a white set, in the style of an 8-bit sprite sheet.
• Two board colour schemes, Sand and Slate (Settings, Board).
• Light and Dark themes, following your phone by default.
• Buttons, tabs and rows respond to touch and hover with press and lift animations. Reduced-motion settings are respected.
• Haptic taps and synthesized sounds (no audio files). Both can be switched off.

Offline and private

• Works in airplane mode once installed. Settings shows whether the app is Ready offline.
• Install it to the Home Screen as a standalone app with its own icon.
• Games, puzzles and progress are stored only on the device. Erase everything wipes them.
• The only network use is the first load.

Put it on your phone (once, with signal)

It's a static site, no build step. Deploy to Vercel:

npx vercel --prod

Or import the repo in the Vercel dashboard (framework: Other, no build command, output dir .).

Then on the phone, while online:

1. Open the URL in Safari (iPhone) or Chrome (Android).
2. Share → Add to Home Screen (Android: Install app).
3. Open it from the home screen once. Settings → Offline should say Ready offline.
4. Test it: airplane mode, reopen, play.

Installing matters on iPhone: Safari can clear a website's stored data after a week of no use, but an app added to the Home Screen is exempt.

Run locally

python3 -m http.server 8099 --bind 127.0.0.1    # then open http://127.0.0.1:8099

(Service workers need https or localhost.)

Updating

Edit anything, redeploy, and bump VERSION in sw.js. Phones pick up the new version the next time they open it with a connection.

Layout

index.html  manifest.webmanifest  sw.js
css/app.css          Design tokens: colours, type, hairlines, easing, Light | Dark
js/app.js            screens and game flow
js/board.js          tap + drag board
js/engine.js         Stockfish worker wrapper (priority queue)
js/store.js, fx.js   local storage; haptics and sound
vendor/              Stockfish 19 lite (1.7 MB wasm), chess.js, pixel-art piece SVGs
icons/               app icon and favicon (the white knight)
scripts/make-pieces.py   generates vendor/pieces from text sprites
scripts/make-icons.py    renders icons/ from the knight sprite (needs Pillow)

Licences

Stockfish is GPLv3 (source: github.com/official-stockfish/Stockfish, and github.com/nmrugg/stockfish.js for the WebAssembly build). If you publish this site, publish its source too. chess.js is BSD-2. Pieces are original (make-pieces.py). Geist is OFL.