I got this idea for a game from another forum. Basically you make a wish, and the person below you will grant it but also corrupt and ruin it in the process.
Here's an example:
Person 1: "I wish for a puppy."
Person 2: "Granted, but it's rabid and bites you. I wish to rule the world."
Person 3: "Granted, you rule for one day but are soon assassinated. I wish for a million dollars."
Ok, let's go!
I wish for the ability to fly!