As an AI language model, I can help you with the logic of creating a simple text-based game like Fallout 4 for a mobile phone using JavaScript. However, due to the complex nature of creating a full-fledged game like Fallout 4 as a single HTML file, it would require significant development effort beyond the scope of a simple response.
Here's a basic example to get you started with a text-based game concept:
This is just a starting point, and you can extend the game using additional HTML, CSS, and JavaScript code. For a complete and fully-featured game like Fallout 4 on a mobile phone, you would typically need separate files for the game assets, multiple scripts, and potentially a server backend.