Sure, here's an example of a Flappy Bird game implemented as a single HTML file using JavaScript and enclosed in script tags:
This is a basic implementation of Flappy Bird that you can play on a smartphone. The bird is controlled by tapping the screen to make it jump. The objective is to navigate the bird through the gaps between the pipes and avoid collision. The game ends when the bird hits the ground or collides with a pipe. Your score is displayed at the top left corner of the game canvas.