Sure! Here's a simple implementation of the game using JavaScript and HTML:
When you open the above HTML file in your smartphone's browser, you'll see a green cube in the center of the screen. If you tap on it, a new green cube will appear at a random position within the game container.
However, if you don't tap on the green cube for 3 seconds, a red cube will appear. If you touch the red cube, 5 gray rats will appear at random positions within the game container.