Sure, here's an example of a simple game written in a single HTML file, using JavaScript and enclosed in script tags. The game is designed for smartphone operation and uses pictograms. This is just a basic example and can be expanded upon to add more features and make it more interactive.
This game creates a canvas element where a particle represented by a red circle moves around the screen. The particle bounces off the walls of the canvas, creating a simple bouncing effect. You can try running it in a browser to see the particle in action.