Hope this still would be useful for someone... Check two things in such situation.
As stated in the Apple GameKit Programming Guide, a signed distribution build app will use the live GC environment, while everything else will use the sandbox. Unless you have the Doodle Jump source and build a debug version to run on your devices it will not work in sandbox mode properly.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.