Sure! Here's an example of a simple indie game where you shoot aliens using JavaScript in a single HTML file:
This is a basic alien shooter game where you control a player using the left and right arrow keys and shoot bullets using the spacebar. Aliens will spawn at random positions from the top and move downwards. If your bullets hit an alien, they will be removed from the game.
Please note that this is just a simplified example and there are many improvements that can be made to enhance the gameplay and visuals.