Sure! Here's an example of a simple platformer game implemented as a single HTML file with JavaScript:
This HTML file defines a simple platformer game with a player represented by a red square and a platform represented by a green rectangle. The player can move left and right using the left and right arrow keys respectively, and can jump using the up arrow key. The player's movement is handled by JavaScript code enclosed within
tags. The game logic is implemented with functions like `movePlayer` and `jumpPlayer`. The game can be played on a smartphone by opening the HTML file in a web browser. Please note that this is a simplified example and can be further enhanced and customized according to your specific requirements.