Sure! Here's a simple game implemented as a single HTML file with JavaScript:
In this game, the blue square can be controlled by dragging your finger on the touchscreen of a smartphone. It moves left or right based on the swipe direction. The objective of the game is to shoot other blue squares by tapping anywhere on the screen, making bullets to appear from the top of the blue square. When a bullet collides with another blue square, the score increases.
Please note that the game logic is simplified for demonstration purposes, and you can modify the code based on your requirements and design preferences.