Gambit — chess, played on thin ice

A complete, client-only chess platform with an arctic-clean interface:

Play Stockfish 18 or pass-and-play with honest clocks, opening identification, zen mode and a keyboard-friendly workspace
Review every finished game like the big platforms do — accuracies, move classifications (Book → Brilliant), an evaluation graph, and one-click jumps to the moments that decided the game
Analysis board for any FEN or PGN with MultiPV engine lines
Puzzle training across seven mechanically verified themes
No account, no server — everything runs in the browser and your profile lives in localStorage.

Run

npm install
npm run dev        # http://localhost:5173
npm run build      # production build in dist/
npm run preview    # serve the production build

Vite + React 19 + TypeScript — app shell, routing via react-router-dom (hash router)
chess.js — all rules: legal moves, check/checkmate/stalemate, draws, en passant, castling, promotion, PGN
react-chessboard — board rendering, drag & drop, right-click arrows
Stockfish 18 (WASM, lite single-threaded) — the opponent at four strengths (UCI Skill Level + depth/time budgets; weak levels sample from MultiPV), plus game analysis. Runs in a Web Worker; a custom negamax engine (alpha-beta, quiescence, piece-square tables) remains as an offline fallback if the WASM can't load
Game review — every position evaluated by Stockfish; moves classified by centipawn loss, per-side accuracy, evaluation graph with weak-move markers, cached per game

Landing page with a live replay of the Opera Game (Morphy, 1858)
Play vs. the engine (4 strengths, ~800–2000 Elo) or pass & play
10 time controls (bullet → classical + no clock) with increment, flag fall, low-time chime
Click-to-move and drag-and-drop, legal-move dots, last-move & check highlights, promotion picker, engine hints (right-drag arrows too)
Undo (full move pair vs. the engine), resign with confirmation, draw offers the engine accepts only when it's worse
Elo-rated games and puzzles stored locally; profile with stats, sparkline, match history
Game review: step through moves with an evaluation bar and the engine's best line
16 mate-in-one puzzles generated and verified by scripts/gen-puzzles.mjs
Light/dark/system themes, four board palettes, sound effects (WebAudio, no assets), responsive down to phones

App code: MIT. public/stockfish/ contains Stockfish builds from stockfish.js, licensed GPL-3.0.

node scripts/gen-puzzles.mjs

Plays random games, keeps positions with exactly one mating move, and writes src/data/puzzles.ts.