Sure, here's an example of a simplified Flappy Bird game implemented as a single HTML file using JavaScript:
To play the game, open the HTML file in a web browser (preferably on a smartphone) and use the space key to control the bird's movement. The goal is to avoid collision with the green pipes while scoring points by passing through the gaps between them. The score is displayed at the top left corner of the game canvas, and the game ends if the bird collides with a pipe or hits the ground. Enjoy playing!