Sure! Here's an example of a simple game implemented as a single HTML file using JavaScript and enclosed in script tags. Please note that this is a basic implementation and may not be a full-fledged 3D game, but rather a 2D game using pictograms.
In this example, the game presents a simple blue square representing the player, and the user can control the player's movement using the keyboard's arrow keys. To further enhance the game, you can implement touch events specific to smartphones or extend the code to include additional game elements, objectives, and interactions based on your desired game concept.