Sure, here's a simple implementation of an infinite run 3D game using JavaScript, enclosed in script tags within a single HTML file. Please note that this is a basic example and can be further expanded with more features and visuals to enhance the gameplay experience:
In this implementation, the game sets up an HTML canvas as the game area and constantly updates the player's position on the canvas, simulating an infinite run game. You can further enhance the game by adding obstacles, power-ups, scoring system, and more.