Sure! Here's an example of a simple text-based game about World War III implemented as a single HTML file using JavaScript:
In this example, the game simulates turns between the player and the enemy, with each turn consisting of both sides attacking and reducing each other's health. The game loop continues until either the player or the enemy's health reaches 0, resulting in a game-over state. The game output is printed in the browser's console for simplicity.
Please note that this is a basic example to give you an idea of how to structure a game using JavaScript within an HTML file. You can enhance it by adding more features, graphics, or interactivity as per your requirements.