A few days back Google celebrated the 30th anniversary of Pac-Man with their first-ever playable Google doodle. It was so popular the Google decided to make the game permanently available at Google.com/Pacman. To activate two player mode click the "Insert Coin" button twice (the button is just below the search bar).
"on PAC-MAN’s 30th birthday, you can rediscover some of your 8-bit memories—or meet PAC-MAN for the first time—through our first-ever playable Google doodle. To play the game, go to google.com during the next 48 hours (because it’s too cool to keep for just one day) and either press the “Insert Coin” button or just wait for a few seconds.
Google doodler Ryan Germick and I made sure to include PAC-MAN’s original game logic, graphics and sounds, bring back ghosts’ individual personalities, and even recreate original bugs from this 1980’s masterpiece. We also added a little easter egg: if you throw in another coin, Ms. PAC-MAN joins the party and you can play together with someone else (PAC-MAN is controlled with arrow keys or by clicking on the maze, Ms. PAC-MAN using the WASD keys)."