Sure! Here's an example of a simple shooting game implemented as a single HTML file with JavaScript:
To play the game on a smartphone, open the HTML file using a mobile web browser. The game allows you to control the player by dragging your finger on the screen. Tap anywhere on the screen to shoot bullets at the falling enemies. Your score will increase for each enemy hit. When an enemy reaches the bottom of the screen, the game is over, and your final score is displayed.