Sure, here's an example of a simple game implemented as a single HTML file, with JavaScript enclosed in script tags:
In this example, the game is a simple canvas-based game where you control a player represented by a white square on the screen. You can touch and drag the player to move it around. The game loop continuously updates the canvas to redraw the player's position.
Please note that this is a basic example and can be expanded upon with additional game mechanics, graphics, and more complex gameplay.