Sure! Here's an example of a simple block game implemented as a single HTML file using JavaScript:
This game creates a simple block that moves down and the player needs to maneuver it by using the left and right arrow keys to avoid collisions with other blocks falling from the top. If a collision occurs, the game ends with an "Game Over!" alert.
To play the game, simply save the above code as an HTML file, open it in a web browser (preferably on a smartphone for the assumed smartphone operation), and interact with it using the arrow keys.