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Add simple web-based snake game #72

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6b6f5f4
Add simple web-based snake game
beta-devin-ai-integration[bot] Apr 7, 2026
202058d
Fix overlay positioning: center Game Over overlay on canvas
beta-devin-ai-integration[bot] Apr 7, 2026
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302 changes: 302 additions & 0 deletions snake-game.html
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Original file line number Diff line number Diff line change
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Snake Game</title>
<style>
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}

body {
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
min-height: 100vh;
background: #1a1a2e;
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
color: #eee;
}

h1 {
margin-bottom: 10px;
font-size: 2rem;
color: #00d2ff;
text-shadow: 0 0 10px rgba(0, 210, 255, 0.5);
}

#score-board {
display: flex;
gap: 30px;
margin-bottom: 10px;
font-size: 1.1rem;
}

#score-board span {
color: #00d2ff;
font-weight: bold;
}

canvas {
border: 2px solid #00d2ff;
border-radius: 4px;
box-shadow: 0 0 20px rgba(0, 210, 255, 0.3);
background: #16213e;
}

#controls {
margin-top: 15px;
font-size: 0.9rem;
color: #888;
text-align: center;
line-height: 1.6;
}

#overlay {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
display: flex;
flex-direction: column;
align-items: center;
justify-content: center;
pointer-events: none;
background: rgba(0, 0, 0, 0.5);
border-radius: 4px;
display: none;
}

#overlay.active {
display: flex;
pointer-events: auto;
}

#overlay-text {
font-size: 1.8rem;
font-weight: bold;
color: #fff;
text-shadow: 0 0 15px rgba(0, 210, 255, 0.8);
}

#restart-btn {
margin-top: 12px;
padding: 10px 28px;
font-size: 1rem;
border: 2px solid #00d2ff;
background: transparent;
color: #00d2ff;
border-radius: 6px;
cursor: pointer;
display: none;
transition: background 0.2s, color 0.2s;
}

#restart-btn:hover {
background: #00d2ff;
color: #1a1a2e;
}
</style>
</head>
<body>
<h1>Snake Game</h1>
<div id="score-board">
<div>Score: <span id="score">0</span></div>
<div>High Score: <span id="high-score">0</span></div>
</div>

<div style="position: relative; display: inline-block;">
<canvas id="game" width="400" height="400"></canvas>
<div id="overlay">
<div id="overlay-text"></div>
<button id="restart-btn">Play Again</button>
</div>
</div>

<div id="controls">
Arrow keys or WASD to move<br>
Press Space or Enter to start / restart
</div>

<script>
const canvas = document.getElementById('game');
const ctx = canvas.getContext('2d');
const scoreEl = document.getElementById('score');
const highScoreEl = document.getElementById('high-score');
const overlayEl = document.getElementById('overlay');
const overlayText = document.getElementById('overlay-text');
const restartBtn = document.getElementById('restart-btn');

const GRID = 20;
const TILE = canvas.width / GRID;
const TICK_MS = 120;

let snake, direction, nextDirection, food, score, highScore, running, gameOver, loopId;

highScore = parseInt(localStorage.getItem('snakeHighScore') || '0', 10);
highScoreEl.textContent = highScore;

function init() {
snake = [
{ x: 10, y: 10 },
{ x: 9, y: 10 },
{ x: 8, y: 10 },
];
direction = { x: 1, y: 0 };
nextDirection = { x: 1, y: 0 };
score = 0;
scoreEl.textContent = score;
gameOver = false;
running = true;
placeFood();
hideOverlay();
clearInterval(loopId);
loopId = setInterval(tick, TICK_MS);
}

function placeFood() {
while (true) {
food = {
x: Math.floor(Math.random() * GRID),
y: Math.floor(Math.random() * GRID),
};
if (!snake.some(s => s.x === food.x && s.y === food.y)) break;
}
}

function tick() {
if (!running) return;

direction = { ...nextDirection };

const head = {
x: snake[0].x + direction.x,
y: snake[0].y + direction.y,
};

// Wall collision
if (head.x < 0 || head.x >= GRID || head.y < 0 || head.y >= GRID) {
return endGame();
}

// Self collision
if (snake.some(s => s.x === head.x && s.y === head.y)) {
return endGame();
}

snake.unshift(head);

if (head.x === food.x && head.y === food.y) {
score++;
scoreEl.textContent = score;
if (score > highScore) {
highScore = score;
highScoreEl.textContent = highScore;
localStorage.setItem('snakeHighScore', highScore);
}
placeFood();
} else {
snake.pop();
}

draw();
}

function draw() {
// Background
ctx.fillStyle = '#16213e';
ctx.fillRect(0, 0, canvas.width, canvas.height);

// Grid lines (subtle)
ctx.strokeStyle = 'rgba(255,255,255,0.03)';
for (let i = 0; i <= GRID; i++) {
ctx.beginPath();
ctx.moveTo(i * TILE, 0);
ctx.lineTo(i * TILE, canvas.height);
ctx.stroke();
ctx.beginPath();
ctx.moveTo(0, i * TILE);
ctx.lineTo(canvas.width, i * TILE);
ctx.stroke();
}

// Snake
snake.forEach((seg, i) => {
const ratio = 1 - i / snake.length;
const g = Math.round(180 + 75 * ratio);
ctx.fillStyle = i === 0 ? '#00ff88' : `rgb(0, ${g}, 100)`;
ctx.shadowColor = i === 0 ? '#00ff88' : 'transparent';
ctx.shadowBlur = i === 0 ? 8 : 0;
ctx.fillRect(seg.x * TILE + 1, seg.y * TILE + 1, TILE - 2, TILE - 2);
});
ctx.shadowBlur = 0;

// Food
ctx.fillStyle = '#ff4757';
ctx.shadowColor = '#ff4757';
ctx.shadowBlur = 10;
ctx.beginPath();
ctx.arc(food.x * TILE + TILE / 2, food.y * TILE + TILE / 2, TILE / 2 - 2, 0, Math.PI * 2);
ctx.fill();
ctx.shadowBlur = 0;
}

function endGame() {
running = false;
gameOver = true;
clearInterval(loopId);
showOverlay('Game Over!');
}

function showOverlay(msg) {
overlayEl.classList.add('active');
overlayText.textContent = msg;
restartBtn.style.display = 'inline-block';
}
Comment on lines +256 to +260

@beta-devin-ai-integration beta-devin-ai-integration Bot Apr 7, 2026

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🔴 Overlay is mispositioned because viewport-relative coordinates are used for an absolutely-positioned child

The #overlay is position: absolute inside a position: relative parent (snake-game.html:106), so its left/top are interpreted relative to that parent. However, showOverlay uses canvas.getBoundingClientRect() which returns viewport-relative coordinates and assigns them directly as left and top. This offsets the overlay by the distance of the container from the viewport origin, causing the "Game Over" overlay and "Play Again" button to appear in the wrong position (shifted far away from the canvas).

Suggested change
function showOverlay(msg) {
overlayEl.classList.add('active');
overlayText.textContent = msg;
restartBtn.style.display = 'inline-block';
}
overlayEl.style.left = '0px';
overlayEl.style.top = '0px';
overlayEl.style.width = rect.width + 'px';
overlayEl.style.height = rect.height + 'px';
Staging: Open in Devin

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@beta-devin-ai-integration beta-devin-ai-integration Bot Apr 7, 2026

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Already fixed in commit 202058d — removed the getBoundingClientRect() approach entirely and replaced it with pure CSS positioning (top: 0; left: 0; width: 100%; height: 100% relative to the parent container). The overlay now centers correctly on the canvas.


function hideOverlay() {
overlayEl.classList.remove('active');
restartBtn.style.display = 'none';
}

// Input
document.addEventListener('keydown', e => {
const key = e.key.toLowerCase();

if ((key === ' ' || key === 'enter') && gameOver) {
e.preventDefault();
init();
return;
}

if (!running) return;

switch (key) {
case 'arrowup': case 'w':
if (direction.y === 0) nextDirection = { x: 0, y: -1 };
break;
case 'arrowdown': case 's':
if (direction.y === 0) nextDirection = { x: 0, y: 1 };
break;
case 'arrowleft': case 'a':
if (direction.x === 0) nextDirection = { x: -1, y: 0 };
break;
case 'arrowright': case 'd':
if (direction.x === 0) nextDirection = { x: 1, y: 0 };
break;
}
});

restartBtn.addEventListener('click', () => init());

// Initial draw & start
init();
draw();
</script>
</body>
</html>