Here's an example of a simple game implemented as a single HTML file using JavaScript and script tags. It is designed for smartphone operation and uses pictograms. Please note that this is just a basic template and you can customize it to add your desired game logic and graphics.
To play the game, you simply need to open the HTML file in a web browser on your smartphone. Upon loading, you will see a "Start Game" button. Clicking this button will begin the game. The objective is to click on the pictograms/buttons as fast as possible within the given time limit. The score will increase each time you click a pictogram/button. After the time runs out, an alert will display the final score.