Sure! Here's a simple basketball game implemented as a single HTML file using JavaScript:
To play the game, you can open the HTML file on a smartphone's web browser, and the game will start automatically. The goal of the game is to bounce the ball off the paddle and prevent it from touching the bottom of the canvas. Use the left and right arrow keys or the corresponding buttons on the touchscreen to move the paddle and keep the ball in play. If the ball touches the bottom of the canvas, a "Game Over" alert will be displayed, and the game will restart when dismissed.
Please note that this is a basic implementation of a basketball game, and you can modify and enhance it further according to your requirements.