Sure! Here is an example of a simple game implemented as a single HTML file, using JavaScript enclosed in script tags. The game displays numbers counting up forever, but each time a new number appears, it increases its speed by 10%. The game can be played on a smartphone and uses pictograms to display the numbers.
To use this game, create a new HTML file and paste the above code into it. Open the HTML file on a smartphone, and you will see the numbers counting up with pictograms appearing at increasing speeds.