Sure! Here's a simple example of a billiards game implemented as a single HTML file using JavaScript and enclosed in script tags:
In this game, three colored balls are moving around the canvas, bouncing off the walls. You can modify the properties of the balls (position, size, color, speed) or add more balls if you'd like. The game runs automatically once the page is loaded.
Please note that this is a very basic example just to give you an idea. A complete billiards game would require much more complex logic and interactions.