Sure! Here's an example of a simple shooting game implemented as a single HTML file:
This game allows you to control a player character (green) using the left and right arrow keys. You can shoot bullets by pressing the spacebar. The goal is to shoot down the enemies (blue) that spawn randomly from the top of the canvas. Each successful hit increases your score. The game runs until you close the browser tab or window.
Please note that this is a basic implementation and can be expanded upon with additional features, graphics, and optimizations.