As an AI text-based model, I can provide you with a sample template for creating a simple game using JavaScript enclosed within HTML script tags. Please note that implementing a full game like GTA 5 within a single HTML file is highly complex and requires extensive resources and development expertise. However, I can guide you in creating a basic game structure. Here's an example:
In this example, a canvas element is used as the game screen, and a simple player object is created and drawn on the canvas. You can add game logic, controls, and additional elements based on your requirements.
Remember that creating a fully functional game like GTA 5 is beyond the scope of a single HTML file, and it requires a team of professionals, a game engine, and extensive development efforts.