Sure! Here's an example of a simple shooting game implemented as a single HTML file using JavaScript. Please copy the code and save it as an HTML file to play the game:
This game allows you to control a blue square (representing the player) using the left and right arrow keys on your smartphone. Pressing the spacebar will fire a red bullet from the player's position. The objective is to hit the green square (representing the enemy) with your bullets while avoiding collision with the enemy. If the player collides with the enemy, it's game over and the page will be refreshed to restart the game.