Html5游戲是當前非常熱門的一種類型游戲，它不但具有良好的跨平臺性和優秀的性能表現，而且還具有豐富多彩的游戲玩法和界面設計。而想要開發一個好的Html5游戲，需要掌握相應的技術和代碼，而今天我們要介紹的就是Html5游戲源代碼免費下載。

Html5游戲源代碼免費下載，是指通過網絡或其他渠道獲取Html5游戲開發所需的源代碼，而且是完全免費的。這些源代碼覆蓋了廣泛的游戲類型，包括動作、策略、角色扮演等等，而且還包含了豐富的游戲元素和特效效果，能夠幫助初學者快速入門Html5游戲開發，也能幫助專業開發者節省時間和勞動力。

下面是一段典型的Html5游戲源代碼，使用pre標簽進行格式化展示：

var game = new Phaser.Game(800, 600, Phaser.AUTO, '', { preload: preload, create: create, update: update });
function preload() {
game.load.image('sky', 'assets/sky.png');
game.load.image('ground', 'assets/platform.png');
game.load.image('star', 'assets/star.png');
game.load.spritesheet('dude', 'assets/dude.png', 32, 48);
}
function create() {
game.physics.startSystem(Phaser.Physics.ARCADE);
game.add.sprite(0, 0, 'sky');
platforms = game.add.group();
platforms.enableBody = true;
var ground = platforms.create(0, game.world.height - 64, 'ground');
ground.scale.setTo(2, 2);
ground.body.immovable = true;
var ledge = platforms.create(400, 400, 'ground');
ledge.body.immovable = true;
ledge = platforms.create(-150, 250, 'ground');
ledge.body.immovable = true;
player = game.add.sprite(32, game.world.height - 150, 'dude');
game.physics.arcade.enable(player);
player.body.bounce.y = 0.2;
player.body.gravity.y = 300;
player.body.collideWorldBounds = true;
player.animations.add('left', [0, 1, 2, 3], 10, true);
player.animations.add('right', [5, 6, 7, 8], 10, true);
cursors = game.input.keyboard.createCursorKeys();
stars = game.add.group();
stars.enableBody = true;
for (var i = 0; i< 12; i++)
{
var star = stars.create(i * 70, 0, 'star');
star.body.gravity.y = 6;
star.body.bounce.y = 0.7 + Math.random() * 0.2;
}
scoreText = game.add.text(16, 16, 'score: 0', { fontSize: '32px', fill: '#000' });
score = 0;
}
function update() {
game.physics.arcade.collide(player, platforms);
game.physics.arcade.collide(stars, platforms);
game.physics.arcade.overlap(player, stars, collectStar, null, this);
player.body.velocity.x = 0;
if (cursors.left.isDown)
{
player.body.velocity.x = -150;
player.animations.play('left');
}
else if (cursors.right.isDown)
{
player.body.velocity.x = 150;
player.animations.play('right');
}
else
{
player.animations.stop();
player.frame = 4;
}
if (cursors.up.isDown && player.body.touching.down)
{
player.body.velocity.y = -350;
}
}
function collectStar (player, star) {
star.kill();
score += 10;
scoreText.text = 'Score: ' + score;
}

以上代碼是一個基本的Html5游戲，使用了Phaser框架，主要實現了角色移動、收集星星、得分等玩法。對于初學者來說，這段源代碼非常適合學習和實踐，同時也可在其基礎上進行更進一步的擴展和創新。

總之，Html5游戲源代碼免費下載是一個在Html5游戲開發中非常有價值的資源，值得開發者們認真學習和使用。