How The Horsey Moves
A free, open-source chess trainer for young students learning how each piece moves. All of this is with LLM help so except for this sentence expect everything to be impossibly cringe.
Built for classroom use — no chat, no ads, no memberships. A teacher introduces chess in a lesson, and students practice the basics here afterward. Designed for settings where one teacher supports ~20 students and can't sit with each one individually.
Live at: howthehorseymoves.net
What it does
- Basics — progressive puzzles for each piece (rook, bishop, queen, king, knight, pawn), plus castling, en passant, a timed coordinate trainer, and a piece placement trainer
- How to Win — guided lesson covering check, checkmate, and stalemate with interactive practice
- Checkmate patterns — back rank, rook ladder, queen-bishop battery, knight on f7, Lolli's mate, queen & king endgames, smothered mate
- Tactics — pins, skewers, forks, removing the defender, discovered attacks (hand-authored instruction + Lichess practice puzzles)
- Endings — King + Pawn vs King (bitbase-powered perfect defense), mate conversion (KQK, KRRK, KRK), and advanced endings (KBBK, KBNK, Philidor "hold the draw" trainer)
- Blindfold training — 24 visualization trainers: color of square, same diagonal, knight routes, knight squares, piece reachability, flash position, move counting, blindfold checkmate, and more
- Play vs computer — an eight-rung ladder of animal opponents, from The Sloth (random moves) up to The Owl (opening book + two-move lookahead), each with an animated avatar and reactions. One opponent per curriculum level; beating one earns a trophy
- Openings — learn opening repertoires move by move with arrow hints
- Model games — 14 classical games (Fool's Mate through Kasparov) with move-by-move viewer, annotations, variation support, and a test mode to reproduce games from memory
- Star ratings — 1-3 stars based on move efficiency, shown as mastery badges when all puzzles in a set are completed
- Sequential unlock — complete a puzzle to unlock the next one
- Sound effects — move, correct, wrong, and star sounds with a mute toggle
- No accounts — progress saves to the browser (localStorage)
- Breathwork (
/breathwork) — a standalone, non-chess extra: a guided breathing trainer (resonance breathing + the cyclic physiological sigh) for performance-coaching students. Not linked from the chess nav
- The Probabilitizer (
/probabilitizer) — a standalone opening-odds explorer: play or paste a line and see the cumulative chance of the whole line arising from the start (split by which side you play), using the Lichess opening explorer. Requires a one-click "Login with Lichess" (Lichess's explorer now needs authentication). Not linked from the chess nav. Based on Opening-Explorer-Plus by EikaMikiku
Running locally
npm install
npm run dev # http://localhost:5173
npm run build # production build
npm run check # svelte-check (TypeScript + Svelte diagnostics)
Requires Node.js 18+.
Adding content
Puzzles live in src/lib/puzzles/. Each file exports an array of puzzles. Three types: route (navigate to target squares), puzzle (Lichess-style tactics from FEN+PGN), and conversion (play against a bot to checkmate or promote):
// Route puzzle — navigate piece to stars, avoid walls
{
type: "route",
id: "rook-01",
title: "Rook Path",
instruction: "Collect all the stars!",
playerPiece: "R",
position: [{ piece: "R", color: "w", square: "a1" }],
walls: ["d4", "d5"],
stars: ["a8", "h1"],
starThresholds: { three: 4, two: 6, one: 8 },
}
// Tactic puzzle — FEN position + PGN solution
{
type: "puzzle",
id: "tactics-fork-01",
title: "Knight Fork",
instruction: "Win material with a fork!",
fen: "r1bqkb1r/pppp1ppp/2n2n2/4p2Q/2B1P3/8/PPPP1PPP/RNB1K1NR w KQkq - 4 4",
pgn: "1. Qxf7#",
}
Model games live in src/lib/games/index.ts. Drop in a PGN string:
{
id: "immortal",
white: "Adolf Anderssen",
black: "Lionel Kieseritzky",
event: "London",
year: 1851,
result: "1-0",
pgn: "1.e4 e5 2.f4 exf4 3.Bc4 ...",
description: "The Immortal Game.",
}
Tech stack
- SvelteKit + Svelte 5 (runes mode) + TypeScript (strict)
- Scoped CSS (no Tailwind)
- SVG chess board with drag-and-drop
- No backend — everything runs client-side
- Deployed on Vercel (free tier)
Contributing
Contributions welcome! Ideas for what would help:
- More puzzles (especially beginner-friendly checkmate patterns)
- More model games
- Accessibility improvements
- Mobile UX polish
- Translations
Open an issue to discuss before starting large changes.
License
GNU Affero General Public License v3.0 — free to use, modify, and deploy, but if you host a modified version, you must share your source code too. In the spirit of Lichess.
Acknowledgments
