Sure, here's a simplified example of a 3D basketball game implemented in a single HTML file using JavaScript. Please note that this example is not a fully-fledged game, but it should serve as a starting point for further development.
This example creates a simple 3D basketball game where the player tries to throw the ball into the hoop. The player can control the ball's movement by touching the screen on their smartphone. When the ball enters the hoop, an alert is displayed with a scoring message and the game is reset.
Please note that this is a basic implementation and there's a lot more that can be added to make it a more complete and engaging game.