Sure! Here's an example implementation of an endless runner game using JavaScript and HTML:
In this game, you control a blue square (the player) using the up and down arrow keys on your smartphone. The goal is to avoid the red rectangles (obstacles) that move towards the player from the right side of the screen. If the player collides with an obstacle, it's game over and the final score is displayed.
Please note that this is a basic implementation to give you an idea of how an endless runner game can be created using JavaScript and HTML. You can further enhance and customize it according to your preferences.