Sure! I can provide you with a simple open world game implemented as a single HTML file using JavaScript. Please find the code below:
This simple game sets up a canvas element and allows the player to control a circle (player object) using arrow keys. The player moves with a fixed speed and the game continuously redraws the canvas to show the updated player position. Feel free to customize this game further to suit your requirements.
Note: Please make sure to save this code as an HTML file and open it in a web browser to play the game.