Sure, I can help you create a simple game using JavaScript, enclosed in script tags within a single HTML file. Here's an example of a game where you have to catch falling objects using your smartphone's touch controls:
To play the game on a smartphone, open the HTML file on the device's browser. The game involves catching falling objects by moving the player horizontally using touch controls. Every caught object increases the score. The game ends when an object touches the bottom of the screen.