Sure! Here's an example of a simple Alien Lost in Earth platformer game implemented as a single HTML file using JavaScript:
In this example, we create a simple platformer game where the player, represented by a green square (alien), can move left and right using the arrow keys and jump using the spacebar. The game loop continuously updates the player's position based on the input and handles collision with the ground.
Please note that this implementation is just a basic example and can be expanded upon with additional features such as obstacles, enemies, levels, etc.