Sure! Here's a basic implementation of a first-person shooter game set in Los Angeles using JavaScript within a single HTML file:
To play the game, simply open the HTML file in a web browser on your smartphone. You can control the player's movement using the arrow keys on your smartphone's keyboard/display.
Please note that this is a very basic implementation of a first-person shooter game and does not include shooting or enemies. It sets up the foundation for player movement within the Los Angeles-themed game setting.