Have the app downloaded for my son, and installed after the store (with my login data) uninstalled on his cell phone again. The game now is not running because it calls for a permanent login the Amazon App Store. Amazon has advised me to contact the software author (MS Deemedya Ltd.). Very customer-friendly, since the problem is certainly in Amazon. Too bad Amazon because I'm really expect from you a better customer service.
Conclusion: put the money in the sand and my son can not play the game. Get this and future apps again in a professional store such. B. Goggle Play, buy.