This is pretty much how I come up with all my ideas: I play 'what if?'
It's Stephen King's favorite game, too, and I imagine a lot of writers play it. Sometimes you don't even have to try. You'll just be driving along somewhere, like maybe to work, and your thoughts are all scattered because it's early and you're not a morning person and you're still kind of thinking about a book you read about a man who buys a magic kingdom cheap (it needs some work), which you enjoyed. The sun is out and it's early spring and you've got the windows open a crack in your old blue Bonneville. And as you come around the curve and pass Duck Puddle Pond you think, what if someone inherited a magic kingdom, except, it's not the nice kingdom of her dreams, it's the other one, the evil one everyone else would like to get rid of. What would she do?
That's how The Way to Dendara was born.
That's how all my stories are born. I play the game.