Sure! Here's an example of a simple shooting game implemented as a single HTML file using JavaScript:
In this game, the player controls a square by moving their finger across the screen on a smartphone. Tapping the screen fires a bullet from the player's position. The objective is to shoot the falling enemies without colliding with them. The player's score increases by 10 for each enemy shot. The game ends when the player collides with an enemy, and their final score is displayed in an alert message. The game can be restarted by reloading the page.
Note: This is a simple example to demonstrate the basic mechanics of a shooting game. You can add more features and polish as per your requirements.