Sure! Here's a simplified version of the Flappy Bird game implemented as a single HTML file:
In this implementation, the game will run on a smartphone when opened in a web browser. The bird is represented by a pictogram set as the background image of a div element. The game starts automatically when the page is loaded, and pressing the Space key on the smartphone's keyboard (or tapping the screen) makes the bird jump. The goal is to navigate the bird through the gap between the pipes without hitting them. The game ends if the bird hits a pipe or falls off the screen, displaying the score achieved. To play again, the page can be reloaded.