Sure! Here's an example of a simple platformer battle game implemented as a single HTML file with JavaScript. In this game, you can control a character using arrow keys on a smartphone, jump, move left and right, and punch enemies represented by emoji "
🥊".
To play the game on a smartphone, open it on a web browser (e.g., Chrome) by copying the code into an HTML file, or use an online HTML editor.
Note: This is a basic implementation just to give you an idea. You can further customize and enhance the game by adding more features, enemies, levels, and additional interactions.