Changing the Wizard of Oz Story

To make my iPad app be more of a unique story, rather than just a copy, I have chosen to use the Wizard of Oz story, but change it from being about Dorothy and friends to being about the Wicked Witch of the West.

After doing so research behind the character, there are several other pieces of media about the world of Oz that I could tie into my story. One of these being a book called "Wicked: The Life and Times of the Wicked Witch of the West".

"The novel is a political, social, and ethical commentary on the nature of good and evil and takes place in The Land of Oz, in the years leading to Dorothy's arrival. The story centers on Elphaba, the misunderstood green-skinned girl who grows up to become the notorious Wicked Witch of the West. Gregory Maguire fashioned the name of Elphaba from the initials of Lyman Frank Baum, L-F-B. The story is divided into five different sections based on the plot location. There is also a prologue where Elphaba is spying on Dorothy and her friends, hearing their gossip about her."

http://en.wikipedia.org/wiki/Wicked:_The_Life_and_Times_of_the_Wicked_Witch_of_the_West

This story is more of an alternate universe, but it fleshes out the character of the Witch of the West more, and I could use this as a part of my story, like a part that branches off and the reader can look through her past to see what really made her so bad in the first place.

In the film, the Witch of the East is killed, which is the Witch of the West's sister. This could be used as a major plot point for sympathising with the Witch, and the reader could see why the Witch wanted revenge on Dorothy in the first place.