Sure! Here's a simple shooting game implemented as a single HTML file using JavaScript:
To play the game, simply copy the code above and save it as an HTML file, then open it in a web browser. On a smartphone, you can tap on the "Shoot" button to start the game, and then tap the screen to shoot the bullet towards the moving target (represented by a red circle). If you hit the target, an alert will appear indicating that you won the game. If the target escapes off the screen, a similar alert will appear indicating that you lost the game.
Feel free to adjust the bullet and target speed by changing the values inside the `moveBullet()` and `moveTarget()` functions, respectively.