HTML5的出現為游戲開發提供了更多的可能性，下面是一份HTML5登山賽車的源碼，希望對開發有所幫助：

var car = {
x: 150,
y: 0,
speed: 0,
acceleration: 0.1,
image: null,
width: 0,
height: 0,
init: function() {
this.image = new Image();
this.image.src = 'car.png';
this.width = this.image.width;
this.height = this.image.height;
},
move: function() {
if (keys[37]) { // left arrow
this.speed -= this.acceleration;
} else if (keys[39]) { // right arrow
this.speed += this.acceleration;
} else {
this.speed *= 0.9;
}
this.x += this.speed;
if (this.x< 0) {
this.x = 0;
this.speed = 0;
} else if (this.x + this.width >canvas.width) {
this.x = canvas.width - this.width;
this.speed = 0;
}
},
draw: function(context) {
context.drawImage(this.image, this.x, this.y);
}
};
var keys = {};
window.addEventListener('keydown', function(e) {
keys[e.keyCode] = true;
}, false);
window.addEventListener('keyup', function(e) {
keys[e.keyCode] = false;
}, false);
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var score = 0;
var intervalId = setInterval(function() {
// draw background
context.fillStyle = 'rgb(200, 200, 200)';
context.fillRect(0, 0, canvas.width, canvas.height);
// update car position
car.move();
// draw car
car.draw(context);
// update score
score += 1;
// display score
context.font = '20px Arial';
context.fillStyle = 'rgb(0, 0, 0)';
context.fillText('Score: ' + score, 10, 20);
}, 30);
car.init();

以上是HTML5登山賽車的源碼，其中包括了小車的移動、鍵盤控制、得分統計等基本功能。HTML5為游戲開發提供了更多的可能性，我們可以使用javascript來控制游戲的行為，使用canvas來繪制游戲界面，希望這個簡單的例子能夠對開發者有所幫助。