Sure! Here's an example of a simple piano game implemented as a single HTML file using JavaScript. It is designed for smartphone operation and uses pictograms as button icons.
In this example, there is a `piano-container` div that represents the piano keys layout. Each piano key is represented by a `piano-key` div, which triggers the `playSound` function when clicked. The `playSound` function alerts a message indicating the note being played.
You can replace the `alert` statement inside the `playSound` function with your own code to play actual sounds corresponding to each note.
Please note that this is a basic implementation and doesn't include actual sound playback. You would need to add that functionality using additional JavaScript code or a library.