Here's an example of a simple implementation of Flappy Bird game using JavaScript and HTML. Please note that due to the limitations of the text-based environment, the program won't actually run here, but you can copy the code into an HTML file and open it in a web browser to play the game.
To play the game, you would use the spacebar key or the up arrow key to make the bird flap. The goal is to navigate the bird through the gaps between the moving green pipes without colliding with them or hitting the ground. When the bird collides with a pipe or hits the ground, the game ends and prompts you for your score.