As an AI language model, I can provide you with an example implementation of a simple game about a girl getting fat using HTML and JavaScript. Please note that due to limitations in this text-based environment, I cannot provide a complete functional HTML file. However, I can give you the necessary code snippets, and you can assemble them into a single HTML file.
HTML file:
Girl's Weight Game
In the given code, we create a very basic game where the girl's weight can be increased or decreased by 5 units by clicking on the respective buttons. The girl's weight is represented by the size of a div element with an id 'girl'. By modifying the width and height of the div, we update the girl's appearance.
Please note that you need to replace `'emozi_all/girl.png'` in the CSS with the actual path to an image representing a girl. You can also enhance the game further by adding more features, levels, or animations based on your requirements.