Google doodle is celebrating 30th anniversary of Pac Man. That’s why when you open Google.com homepage, you see a screenshot of the actual Pac Man game.
If you’ve noticed, I’m feeling lucky button has been replaced by Insert Coin button. If you actually press Insert Coin button, it’ll actually start the game which you can play on Google’s homepage.
So celebrate the 30th anniversary of Pac Man by going to Google.com and playing Pac Man. Enjoy!