Sure! Here's an example code implementation of a simplified version of Flappy Bird game using HTML, CSS, and JavaScript, all within a single HTML file:
To play, save the above code into an HTML file, open it in a web browser, preferably on a smartphone, and then tap the screen to make the character (yellow rectangle) fly upwards and avoid the obstacles (green rectangles). The score will be shown in the top right corner, and the game will end if the character collides with any obstacle.
Note: This is a simplified version of Flappy Bird and may not contain all the features or aesthetics of the original game, but it should provide a basic playable experience.