Sure! Here's an example of a simple FPS shooter game implemented as a single HTML file using JavaScript. Since it's a simple implementation, it may not have a lot of detail and quality, but I hope you find it enjoyable to play on a smartphone.
Note: This is a basic template to get you started. You can add more features, graphics, and enhance the gameplay as per your requirements.
To play the game on a smartphone, you can open the HTML file using a web browser. The game simulates a player represented as a red rectangle that can be controlled using touch events. You can customize the game elements, controls, and add more interactions to enhance the gameplay and visuals.