Not that you need another reason to mindlessly hang out on your phone, but for nostalgia's sake, this is a pretty good excuse. You can play the classic version of Pac-Man on your smartphone, and it feels just like old times.
Chow down on ghosts Blinky, Pinky, Inky and Clyde, and complete mazes to receive coins. The coins buy you entry into more mazes and unlock them so you can go back and play them anytime. Or you can play in tournament mode to receive medals.
Obviously your phone doesn't come with a joystick (although, that would be pretty cool), so instead, swipe your finger in the direction you want Pac-Man to go.
Here's the game in action, in case you need a visual reminder of its awesomeness: