Sure! Here's a single HTML file that implements the game you described, with changing styles, cookies, and background every 10 seconds:
Cookie Clicker Game
🍪
Score: 0
To play the game, simply open the HTML file in a web browser, and you'll see a cookie in the center of the screen. Every 10 seconds, the style, cookie, and background will change randomly. Click on the cookie to increase your score. After 30 seconds, the background will change back to normal.
Note that the pictograms used for the cookies ('
🍪', '
🍩', '
🍦') may not render correctly in all browsers or devices, but they are standard Unicode characters that represent the respective pictograms.