GTA: Zombie Mart
The dead has risen from the ground and eats the living. Soon, only a small percentage of humans were left. But, as time passes by, the zombies evolve thus, they are not eating people anymore. They learned to be civilized thus, they learn to shop for whatever they want to eat in shopping marts. In this game, you would be serving the zombies. You would need to make your own store where the zombies could purchase whatever they want, thus, you would make money from them. You would need to make some profit and you need to reach a goal, so that you can continue with your store.