Sure, here's an example of an Atari Pong game with 2 balls implemented as a single HTML file using JavaScript:
This HTML file sets up a game canvas with two paddles (`player1` and `player2`) and two balls (`ball1` and `ball2`). Each ball has its own position and velocity (speed). The game loop (`setInterval(update, 1000 / 60)`) updates the ball positions, handles collisions, and renders the game elements on the screen. Player 2 can control their paddle using the up and down arrow keys.
Please note that this is a basic implementation and may require further improvements depending on your specific requirements and preferences. You can also enhance the game by adding more features, such as keeping score, implementing AI for player 1, or customizing the game visuals.