Sure, here's a simple Billiards game implemented as a single HTML file using JavaScript:
This game will display a billiards ball bouncing around on a canvas. When the ball hits the top boundary of the canvas, it will bounce back up. However, if the ball hits the bottom boundary of the canvas, the game will end and display a "Game Over" message. The game will then be automatically restarted.
Please note that this is a very basic implementation and does not include advanced billiards mechanics or gameplay features. You can enhance the game further as per your requirements.