Add terminal Snake game in Node.js

Zero-dependency, fully playable Snake with ANSI colors, box-drawn
border, score/high-score tracking, and title screen.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

snake.js

@@ -0,0 +1,197 @@
+#!/usr/bin/env node
+'use strict';
+
+const readline = require('readline');
+
+// --- Config ---
+const W = 40, H = 20;
+const TICK = 100; // ms per frame
+
+// --- ANSI helpers ---
+const ESC = '\x1b[';
+const cls = () => process.stdout.write('\x1bc');
+const hide = () => process.stdout.write(ESC + '?25l');
+const show = () => process.stdout.write(ESC + '?25h');
+const move = (x, y) => process.stdout.write(ESC + `${y};${x}H`);
+const color = (code, s) => `\x1b[${code}m${s}\x1b[0m`;
+const green  = s => color('32;1', s);
+const yellow = s => color('33;1', s);
+const red    = s => color('31;1', s);
+const cyan   = s => color('36;1', s);
+const white  = s => color('37;1', s);
+const dim    = s => color('2', s);
+
+// --- State ---
+let snake, dir, nextDir, food, score, highScore = 0, running, timer;
+
+function randPos() {
+  return { x: 1 + Math.floor(Math.random() * (W - 2)), y: 1 + Math.floor(Math.random() * (H - 2)) };
+}
+
+function spawnFood() {
+  let pos;
+  do { pos = randPos(); }
+  while (snake.some(s => s.x === pos.x && s.y === pos.y));
+  food = pos;
+}
+
+function init() {
+  const mid = { x: Math.floor(W / 2), y: Math.floor(H / 2) };
+  snake = [mid, { x: mid.x - 1, y: mid.y }, { x: mid.x - 2, y: mid.y }];
+  dir = { x: 1, y: 0 };
+  nextDir = { x: 1, y: 0 };
+  score = 0;
+  spawnFood();
+  running = true;
+}
+
+function drawBorder() {
+  const top    = cyan('╔' + '═'.repeat(W - 2) + '╗');
+  const bottom = cyan('╚' + '═'.repeat(W - 2) + '╝');
+  move(1, 1); process.stdout.write(top);
+  move(1, H); process.stdout.write(bottom);
+  for (let row = 2; row < H; row++) {
+    move(1, row);    process.stdout.write(cyan('║'));
+    move(W, row);    process.stdout.write(cyan('║'));
+  }
+}
+
+function drawStatus() {
+  move(1, H + 1);
+  process.stdout.write(
+    white(' Score: ') + yellow(String(score).padEnd(6)) +
+    white(' Best: ')  + yellow(String(highScore).padEnd(6)) +
+    dim(' [←↑→↓] move  [q] quit')
+  );
+}
+
+function drawGame() {
+  // Clear interior
+  for (let row = 2; row < H; row++) {
+    move(2, row);
+    process.stdout.write(' '.repeat(W - 2));
+  }
+
+  // Food
+  move(food.x, food.y);
+  process.stdout.write(red('◆'));
+
+  // Snake
+  snake.forEach((seg, i) => {
+    move(seg.x, seg.y);
+    process.stdout.write(i === 0 ? green('█') : green('▓'));
+  });
+
+  drawStatus();
+}
+
+function tick() {
+  dir = nextDir;
+  const head = { x: snake[0].x + dir.x, y: snake[0].y + dir.y };
+
+  // Wall collision
+  if (head.x <= 0 || head.x >= W || head.y <= 0 || head.y >= H) {
+    return gameOver();
+  }
+  // Self collision
+  if (snake.some(s => s.x === head.x && s.y === head.y)) {
+    return gameOver();
+  }
+
+  snake.unshift(head);
+
+  if (head.x === food.x && head.y === food.y) {
+    score++;
+    if (score > highScore) highScore = score;
+    spawnFood();
+  } else {
+    snake.pop();
+  }
+
+  drawGame();
+}
+
+function gameOver() {
+  running = false;
+  clearInterval(timer);
+
+  const msg = red('  GAME OVER  ');
+  const sub = `  Score: ${yellow(String(score))}  `;
+  const reLine = `  Press ${green('r')} to restart or ${red('q')} to quit  `;
+
+  const cx = Math.floor(W / 2) - 12;
+  const cy = Math.floor(H / 2) - 1;
+  move(cx, cy);     process.stdout.write('┌' + '─'.repeat(28) + '┐');
+  move(cx, cy + 1); process.stdout.write('│' + msg.padEnd(28 + msg.length - 13) + '│');
+  move(cx, cy + 2); process.stdout.write('│' + sub.padEnd(28 + sub.length - 14) + '│');
+  move(cx, cy + 3); process.stdout.write('│' + reLine.padEnd(28 + reLine.length - 27) + '│');
+  move(cx, cy + 4); process.stdout.write('└' + '─'.repeat(28) + '┘');
+}
+
+function startGame() {
+  cls();
+  hide();
+  init();
+  drawBorder();
+  drawGame();
+  timer = setInterval(tick, TICK);
+}
+
+// --- Input ---
+readline.emitKeypressEvents(process.stdin);
+if (process.stdin.isTTY) process.stdin.setRawMode(true);
+
+process.stdin.on('keypress', (_, key) => {
+  if (!key) return;
+
+  if (key.name === 'q' || (key.ctrl && key.name === 'c')) {
+    clearInterval(timer);
+    show();
+    cls();
+    move(1, 1);
+    console.log(white('Thanks for playing! Final score: ') + yellow(String(score)));
+    process.exit(0);
+  }
+
+  if (!running) {
+    if (key.name === 'r') { startGame(); }
+    return;
+  }
+
+  const moves = {
+    up:    { x: 0,  y: -1 },
+    down:  { x: 0,  y:  1 },
+    left:  { x: -1, y:  0 },
+    right: { x: 1,  y:  0 },
+  };
+
+  const next = moves[key.name];
+  if (!next) return;
+
+  // Prevent 180° reversal
+  if (next.x === -dir.x && next.y === -dir.y) return;
+  nextDir = next;
+});
+
+// --- Title screen ---
+cls();
+move(1, Math.floor(H / 2) - 3);
+const logo = [
+  ' ███████╗███╗  ██╗ █████╗ ██╗  ██╗███████╗',
+  ' ██╔════╝████╗ ██║██╔══██╗██║ ██╔╝██╔════╝',
+  ' ███████╗██╔██╗██║███████║█████╔╝ █████╗  ',
+  ' ╚════██║██║╚████║██╔══██║██╔═██╗ ██╔══╝  ',
+  ' ███████║██║ ╚███║██║  ██║██║  ██╗███████╗',
+  ' ╚══════╝╚═╝  ╚══╝╚═╝  ╚═╝╚═╝  ╚═╝╚══════╝',
+];
+logo.forEach((line, i) => { move(1, Math.floor(H / 2) - 3 + i); process.stdout.write(green(line)); });
+move(1, Math.floor(H / 2) + 4);
+process.stdout.write(white('  Use ') + cyan('arrow keys') + white(' to move  ·  ') + yellow('eat ◆ to grow') + white('  ·  ') + red('q') + white(' to quit'));
+move(1, Math.floor(H / 2) + 6);
+process.stdout.write(white('         Press ') + green('any arrow key') + white(' to start...'));
+
+// Start on first keypress
+process.stdin.once('keypress', (_, key) => {
+  if (key && (key.ctrl && key.name === 'c')) process.exit(0);
+  startGame();
+});