Sure! Here's a basic example of a 3D open world game implemented as a single HTML file using JavaScript. Please note that this is a simplified version, and you can expand upon it to create a more complex and interactive game.
This code sets up a simple 3D open world game where you control a player object using arrow keys on your smartphone. The game utilizes the `<canvas>` element to draw the player on the screen and update its position based on user input. It's a basic starting point from where you can build and expand the functionality and visual aspects of the game.