Just to get her brain working, I asked her to design me a game, and she went a bit overboard. I just gave her one word to get her started, "merponycorn". That is, of course, an ad-hoc neologism describing a unicorn pony that lives under the sea. . .
A little while later she returned with the main layout of "Ponytopia", showing all the main locations, like the Candy Kingdom, the Beach, the Resort, the Apartment Building, the Fun House, and the Young Club. The Apartment Building is where all the merponycorns live, and when you sign up you get a room you can customize.
Here are the five races of merponycorns, specifically the Pop Star Merponycorn, the Princess Merponycorn, the Fairy Merponycorn, the Magic Merponycorn, and the Rainbow Merponycorn. Each race of merponycorn has different attributes and powers.
Finally, here's some miscellaneous notes regarding how to get points and spend them as well as the merponycorn dress-up application. She went quite far describing the economics of Ponytopia, as economics are a big cornerstone of every virtual world. Apparently you play games to get Ponycoins which you can then use to buy seeds and plant flowers in your virtual garden. Some flowers will sprout into pets that will follow you around and you can care for.
Here's her page of miscellaneous notes.
Oddly I think she's on to something here. Unfortunately, it's quite a bit bigger than a one-person project (as I feel I'll end up doing all the code), and even if I did go with an off-the-shelf solution like Electroserver for much of the underpinnings, there's still a lot there.
So I thought I'd share it as an example of what you get when you tell a little kid to design a game based on a single word. I was really hoping more for "make your merponycorn jump on bubbles to win points" than a whole friggin MMORPG.