Sure! Here's an example of a simple game implemented as a single HTML file using JavaScript:
In this game, the player is represented as a red rectangle on a canvas. The player can be controlled using the left and right arrow keys on a smartphone. The game continuously clears the canvas and redraws the player's position based on the user's input.
Note that this is a very basic example, and you can build upon it to add more features and complexity to the game.