Sure! Here's an example of a simple shooter game implemented as a single HTML file using JavaScript:
In this game, you control a blue circle representing the player using the arrow keys on your smartphone. Pressing the spacebar shoots a red bullet towards the green enemy circle. If the bullet collides with the enemy, the game is over, and an alert is shown. The game will then be automatically reset. The game loop continuously redraws the game elements and checks for collisions. The game is enclosed within `
` tags and can be run as a single HTML file.