Sure! Here's an example of a basic 3D first-person shooter game implemented as a single HTML file using JavaScript. Please note that this is a simplified example and does not have advanced features like complex level design or enemy AI.
You can add your own logic to handle player movements, shooting, collision detection, and other game elements based on your requirements. This example provides a basic structure to get you started with a 3D first-person shooter game using JavaScript in a single HTML file.