Son Number Two is a genius. He has wicked computer design skills and an artist's eye for how to employ them. One of his current games of choice is Roblox, a Lego-like building program that lets you design and move around in your own worlds. I watched him build a world with different levels and spinning things and elevators. Then he sat back and said, "I'm not really sure what to do with this place now."
My reply was quick and firm. "Zombies. You can never go wrong with zombies."
And, thinking about it, that's right. If you are designing a system that encourages people to move through it in some way or another, whether it's a game or a corporate voice mail system, there must be something that keeps people on their toes. Use their brains, so to speak. Thus, you can never go wrong with zombies.