Sure, I can help you create a simple 3D game using JavaScript enclosed in script tags within a single HTML file. However, please note that while I can assist you with the code, it would be better if you have some basic understanding of HTML and JavaScript.
Here's an example of a simple 3D game called "Roblox Game" using pictograms:
In this game, a simple 3D cube is displayed and continuously rotates. You can view this game in your browser, preferably on a smartphone, and see the rotating cube.
Please note that this is a basic example, and you can expand it further by adding more elements, controls, and interactions according to your requirements.