The app is supposed to launch, at some point today.
http://www.ign.com/articles/2014/10/20/simpsons-world-launches-october-21st-every-single-episode-in-one-intuitive-app?abthid=5445466e42e5b0533300000e
http://www.ign.com/articles/2014/10/20/simpsons-world-launches-october-21st-every-single-episode-in-one-intuitive-app?abthid=5445466e42e5b0533300000e