Tiny Tower is a simple, 8-bit graphics game. You own a tower in an urban metropolis, and your goal is to make money and build floors. You start out by making a residential floor and moving people in. Then, you make a store and give the people who live on the residential floor jobs at the store. You make money from the store, and have to constantly keep the items in stock (and pay and even wait to restock it).
Once you have enough money, you can build another floor with another store.
And you just keep going trying to make your tower as high as possible. One of the coolest aspects of the game is that you have to wait; it takes time to restock supplies in your stores, and it can take hours to construct a new floor.
And having gritty, 8-bit graphics just makes the whole thing even more addicting.
Tiny Tower is compatible with the iPhone, iPod Touch, and iPad for a wallet-loving $0.