Sure! Here's a simple 3D running game implemented in a single HTML file using JavaScript and enclosed in script tags:
To play the game, you can copy the above code and save it in an HTML file (e.g., `game.html`). Then, open the file in a web browser on your smartphone. The game will start automatically, and you can control the player's jump by pressing the "ArrowUp" key on a smartphone keyboard.
Please note that this is a simple example meant to provide a starting point for a 3D running game. You can customize and enhance it further based on your requirements and desired features.