Here is a simple example of a game implemented as a single HTML file with JavaScript enclosed in script tags:
This simple game code sets up a canvas element and draws a blue square as the player. The `update` and `draw` functions can be used to update the game logic and draw the game elements respectively. The `gameLoop` function uses `requestAnimationFrame` to continuously update and draw the game. You can expand on this code to add more game elements and interactions.