Do I have to pay $12.99 to accept someone's challenge?
This is awkward. Some random person has sent me a challenge. Except, instead of an "Accept" button, it's "$12.99".
Is this a bug? A scam or what?
The lack of profile pictures was me not giving the Game Center app time to load them.
Solution 1:
That 13 dollar fee is the price of the app your opponent is challenging you on. Make sure you have the app installed, and if not, search to see how much it is. That is the most probable answer to your problem. If you still need help, search through this forum post, as it should cover any additional questions you may have.