Here's an example of a simple implementation of Atari Pong game with 12 balls using HTML and JavaScript. Please note that this is a basic implementation and may not include all features and optimizations of a complete game.
To play the game, simply save the code above into a single HTML file and open it in a web browser. You should be able to control the paddle using the left and right arrow keys, and try to prevent the balls from touching the bottom wall.
Note: This implementation may not be optimized for all devices and performances. It's recommended to further enhance and optimize the code as needed.