Here's another great reply to this question that I got when I posted this same topic on another board. It was from a poster named Shepchap.
"I would make mine like sim city 4. I would make it all nice with peace and then one day send some aliens down to stir in some trouble. Than create some fires to stir the land up a bit and in the end rebuild everything."
That's a cool idea, it sounds like the God of the Bible. And here's another idea I got. I posted this.
"If I could build my own world, it would look like the picture below and I'd create Jesus and God from human cloning and everyday we'd watch Shepherd's Chapel on TV."

I also wrote this.
"This is the picture I was talking about. I'd make mine like the 2nd picture from the left."
So, do you all have any new ideas for worlds you would like to create? If so, please post them here.