Sure! Here's an example of an endless runner game implemented as a single HTML file using JavaScript:
In this game, you control a dog with a hat on its head by jumping over obstacles. The goal is to see how far you can run without hitting an obstacle. The game starts automatically, and you can control the dog's jumps by pressing the Spacebar on your smartphone keyboard.
Please note that this is a basic implementation, and you can customize the game's appearance and mechanics according to your preferences.