My brother, who's an acupuncturist in New York City, sent my kids an Atari game console for the iPad for Christmas. It's essentially a dock with a joystick and four buttons. Like many iPad games, the basic setup is free, and extra games are available as in-app purchases (i.e., not through the iTunes store, but through the app itself).
I downloaded Battlezone, and the kids spent some time playing it. I then gave them a little masterclass in how to play; put another way, I blew away all their high scores. Though I spent more of my college hours in front of one of those machines than I really want to recall.
It's impressive how well the game plays on a completely different platform.