Sure! Here's an example of a simple game where you can move around and score points by touching objects. It uses HTML, CSS, and JavaScript. To keep it as a single HTML file, I've wrapped the JavaScript code within script tags. The game can be played on a smartphone.
Score: 0
In this game, there is a red square that represents the player, and a blue square that represents the object. You can move the player by touching the screen and the object will move randomly. Whenever the player touches the object, the score will increase by 1, which is displayed in the score container. The gameContainer div serves as the game area. You can adjust the width and height as per your preference.