Sure, here's an example of a simple stickman fighting game implemented as a single HTML file using JavaScript:
In this game, you can control the stickman's position using your mouse on a smartphone. The stickman will follow your finger's movements. When you tap the screen, the stickman will perform an attack using a sword. The stickman's health is displayed as a green bar above it, and the game will end if the stickman's health reaches zero.
Please note that this is a very basic implementation and can be expanded upon with additional features such as enemy stickmen, different weapons, levels, etc.