Sure, here's a simple implementation of a billiards game written in a single HTML file using JavaScript and enclosed in script tags:
This simple billiards game includes a cue ball and three object balls. The user can click on the canvas to set the initial velocity of the cue ball and start the game. The game loop continuously updates and redraws the positions of the balls on the canvas using the `requestAnimationFrame` method.
Please note that this is a basic implementation and doesn't include advanced features such as collisions, scoring, or game rules. You can enhance it further based on your requirements.