Sure! Here's an example of a simplified version of Super Mario Bros implemented as a single HTML file:
This code creates a simple game interface with a player controlled by arrow keys and an enemy that moves from right to left. The player and enemy are represented by pictogram-like objects (which you would need to replace with actual image URLs). You can play the game by opening it in a web browser on your smartphone and using the arrow keys to move the player. The enemy moves automatically every 100 milliseconds.