Sure, here's an example of a game where you need to click a green circle to win. However, please note that the onion-secret feature is not available in plain HTML and JavaScript. It's just a fictional element added as per your request.
You can copy and save the above code into a single HTML file and open it in a web browser on your smartphone to play the game. Remember that the onion-secret feature is just imaginary and does not actually change the circle into an onion.