```html
Snake
Snake
Score: 0
High: 0
Arrow keys or WASD to move · Space to start/pause · R to restart
```
```typescript
type Cell = { x: number; y: number };
type Direction = { x: number; y: number };
const GRID = 20;
const CELL = 20;
const INITIAL_TICK_MS = 150;
const MIN_TICK_MS = 60;
const SPEEDUP_EVERY = 5;
const SPEEDUP_DELTA = 10;
class Game {
private canvas: HTMLCanvasElement;
private ctx: CanvasRenderingContext2D;
private scoreEl: HTMLElement;
private highEl: HTMLElement;
private snake: Cell[] = [];
private dir: Direction = { x: 1, y: 0 };
private pendingDir: Direction | null = null;
private food: Cell = { x: 0, y: 0 };
private score: number = 0;
private high: number = 0;
private tickMs: number = INITIAL_TICK_MS;
private alive: boolean = true;
private started: boolean = false;
private paused: boolean = true;
private timer: number | null = null;
constructor(canvas: HTMLCanvasElement, scoreEl: HTMLElement, highEl: HTMLElement) {
this.canvas = canvas;
this.ctx = canvas.getContext('2d')!;
this.scoreEl = scoreEl;
this.highEl = highEl;
const savedHigh = localStorage.getItem('snake.high');
this.high = savedHigh ? parseInt(savedHigh, 10) : 0;
this.restart();
}
public start(): void {
if (!this.started) {
this.started = true;
this.paused = false;
this.runTick();
}
}
public togglePause(): void {
if (this.started && this.alive) {
this.paused = !this.paused;
if (!this.paused) this.runTick();
else if (this.timer) clearTimeout(this.timer);
}
}
public restart(): void {
this.snake = [
{ x: 10, y: 10 },
{ x: 9, y: 10 },
{ x: 8, y: 10 }
];
this.dir = { x: 1, y: 0 };
this.pendingDir = null;
this.score = 0;
this.tickMs = INITIAL_TICK_MS;
this.alive = true;
this.started = false;
this.paused = true;
if (this.timer) clearTimeout(this.timer);
this.timer = null;
this.spawnFood();
this.updateUI();
this.draw();
}
private spawnFood(): void {
let newFood: Cell;
while (true) {
newFood = {
x: Math.floor(Math.random() * GRID),
y: Math.floor(Math.random() * GRID)
};
if (!this.snake.some(seg => seg.x === newFood.x && seg.y === newFood.y)) break;
}
this.food = newFood;
}
private updateUI(): void {
this.scoreEl.innerText = `Score: ${this.score}`;
this.highEl.innerText = `High: ${this.high}`;
}
private runTick(): void {
if (!this.alive || this.paused) return;
this.update();
this.draw();
this.timer = window.setTimeout(() => this.runTick(), this.tickMs);
}
private update(): void {
if (this.pendingDir) {
this.dir = this.pendingDir;
this.pendingDir = null;
}
const head = {
x: this.snake[0].x + this.dir.x,
y: this.snake[0].y + this.dir.y
};
// Wall collision
if (head.x < 0 || head.x >= GRID || head.y < 0 || head.y >= GRID) {
this.gameOver();
return;
}
// Body collision (ignore tail cell that is vacating)
for (let i = 0; i < this.snake.length - 1; i++) {
if (this.snake[i].x === head.x && this.snake[i].y === head.y) {
this.gameOver();
return;
}
}
this.snake.unshift(head);
if (head.x === this.food.x && head.y === this.food.y) {
this.score++;
if (this.score > this.high) {
this.high = this.score;
localStorage.setItem('snake.high', this.high.toString());
}
this.updateUI();
this.spawnFood();
if (this.score % SPEEDUP_EVERY === 0) {
this.tickMs = Math.max(MIN_TICK_MS, this.tickMs - SPEEDUP_DELTA);
}
} else {
this.snake.pop();
}
}
private gameOver(): void {
this.alive = false;
if (this.timer) clearTimeout(this.timer);
this.draw();
}
private draw(): void {
this.ctx.fillStyle = '#000';
this.ctx.fillRect(0, 0, this.canvas.width, this.canvas.height);
// Food
this.ctx.fillStyle = '#c0392b';
this.ctx.fillRect(this.food.x * CELL, this.food.y * CELL, CELL, CELL);
// Snake
this.snake.forEach((seg, i) => {
this.ctx.fillStyle = i === 0 ? '#7ed957' : '#3aa635';
this.ctx.fillRect(seg.x * CELL, seg.y * CELL, CELL, CELL);
});
this.ctx.fillStyle = '#fff';
this.ctx.font = '20px sans-serif';
this.ctx.textAlign = 'center';
this.ctx.textBaseline = 'middle';
if (!this.started) {
this.ctx.fillText('Press Space to start', 200, 200);
} else if (this.paused && this.alive) {
this.ctx.fillText('Paused', 200, 200);
} else if (!this.alive) {
this.ctx.fillText('Game Over — press R to restart', 200, 200);
}
}
public setDirection(nx: number, ny: number): void {
// Prevent reverse-into-self
if (nx === -this.dir.x && ny === -this.dir.y) return;
this.pendingDir = { x: nx, y: ny };
}
}
const canvas = document.getElementById('game') as HTMLCanvasElement;
const scoreEl = document.getElementById('score') as HTMLElement;
const highEl = document.getElementById('high') as HTMLElement;
const game = new Game(canvas, scoreEl, highEl);
window.addEventListener('keydown', (e) => {
switch (e.key) {
case 'ArrowUp': case 'w': case 'W':
e.preventDefault(); game.setDirection(0, -1); break;
case 'ArrowDown': case 's': case 'S':
e.preventDefault(); game.setDirection(0, 1); break;
case 'ArrowLeft': case 'a': case 'A':
e.preventDefault(); game.setDirection(-1, 0); break;
case 'ArrowRight': case 'd': case 'D':
e.preventDefault(); game.setDirection(1, 0); break;
case ' ':
e.preventDefault();
if (!game.started) game.start();
else game.togglePause();
break;
case 'r': case 'R':
e.preventDefault();
game.restart();
break;
}
});
```