If you are suffering from crashes or the game failing to run please try fully restarting the device as a first step.
To turn the device off: Press and hold the Sleep/Wake button for a few seconds until the red "slide to power off" slider appears, and then slide the slider.
To turn it on again: Press and hold the Sleep/Wake button until the Apple logo appears. It will then boot up in a few seconds.
If you are still suffering issues, please report these by email at email@example.com and we will investigate further for you. It may be helpful if you could send us your save file. There are instructions on how to do this attached.
If the game fails to run immediately after purchasing and installing it, it is possible that it may not have downloaded or installed correctly. In this situation, it is best to delete the app from your device, reboot the device fully and then re-install the app. iTunes will know that you have already purchased the app and will let you download it again. Make sure you the game isn't running before doing this!