Sure, here's an example of a simple game implemented as a single HTML file with JavaScript using the canvas element for graphics and the matter.js library for physics simulation. The game involves controlling a circle using touch on a smartphone to navigate it through a maze-like environment.
You can save the above code into an HTML file and open it in a web browser to play the game. On a smartphone, you can touch and drag the circle to move it around. The circle has physics applied to it, allowing it to bounce off walls and other objects.