Sure! Here's an example of a basic 3D FPS game implemented as a single HTML file using JavaScript. Please note that this is a simplified version for demonstration purposes, and you may need to enhance it further to add game logic, animations, controls, etc.
This is a basic template for a 3D FPS game. You can enhance it further by adding graphics, textures, controls, collision detection, enemy AI, and other game-specific features. It's important to note that developing a fully-featured 3D FPS game is a complex task that would require advanced programming techniques, libraries, and frameworks. The provided example is just a starting point.