First of all here is my hardware:
iPad Air 2 with128Mb storage.
I had 4 times the same problem: I have a modem to have an internet connection while playing. My internet connection is only Available in one country. When I get back home I have my modem that cut the connection and display a welcome page instead of my sites. If I happen to playing while this disconnection occurs then the game is corrupted and here is no way to restart the game after the crash. This doesn't happen if I'm playing without wifi even if I stop my connection while playing. To my mine this is related to the splash screen that is displayed on my modem when I'm connected to wifi but there is no internet.
After such a crash the only solution I've found is to reinstall the game as there is no way to start it.
I hope you'll Try to fix this behavior. Thanks