Sure! Here's an example of a simple 2D shooter game implemented as a single HTML file using JavaScript and enclosed in script tags:
This game sets up a canvas element where the player, represented by a square, can move using the arrow keys on a smartphone. The player's position is updated based on the keypress event, and the game loop continuously redraws the player's position on the canvas.
Please note that this is a very basic example and can be expanded upon to include enemies, shooting mechanics, and more complex gameplay features.