Sure, here's a simple text-based game called "Bus Simulator 21" implemented as a single HTML file:
This implementation is a simple "Bus Simulator 21" game where the player chooses a destination by entering a number, and the bus arrives at that location. The game output is displayed in a `pre` HTML element. The game starts by calling the `startGame()` function.
Feel free to modify and enhance this code to suit your game requirements.