Sure, here's an example of a simple war game implemented as a single HTML file using JavaScript:
War Game
Play
In this example, the game begins when the "Play" button is clicked. The game randomly selects a winner between two players represented by pictograms, and the result is displayed on the page. The "Play" button is hidden once the game starts to prevent multiple games from being played simultaneously.
Note that this is a basic example and can be further expanded and customized to suit your desired gameplay and game mechanics.