Pizza. It's pretty popular for the most part, so really it was just a question of time before it came to the iPad. While Pizza Hut was first with an iPad app, Domino's is the first with a game. Domino's Pizza Hero is that game, and like most rhythm type games, it's quite a bit of fun.
This app has some bonuses though: You can progress through levels and learn the magic of pizza creation, and when you have it all figured out, you can walk through the process of building the pizza of your dreams, and then place an order through the app for that very pizza. It's a lot of fun, and the ordering process looks pretty straightforward.
My only real complaint is that the feedback in the app as you complete levels is sometimes contradictory. "Great job with the sa