Hello there Mr-unarmed94,
Thanks for posting here on the Apple Support Communities! This is a place where other Apple users can submit questions or respond to others to help lend a hand.
We see you're having some issues with this specific app. Let's take a closer look as we do our best to provide some additional insight.
To get started, does this continue even after signing in to the Game Center? Also, do you experience the same issues with any other apps at all? If not, let’s try completing these steps: If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open
If issues persist after completing those steps, we’d next suggest reaching out to the app developer for additional help troubleshooting the functionality of their application. You can use these steps to help locate their contact information: How to contact an app developer
We hope this helps get you pointed in the right direction!
Take care.