As a language model AI, I can provide you with a simple example of a retro-style game implemented as a single HTML file. Here's an example of a classic snake game using JavaScript:
This example successfully creates a playable snake game using the HTML canvas element and JavaScript. The game involves controlling the snake's movement using arrow keys, collecting food, and avoiding collisions with the walls and the snake's body. The game renders a grid-like board and updates the game state on each frame.