Why i can’t pay for app game

Hello ~ What happens when you try? Any messages or errors? Perhaps because you have an iPhone with iOS 12 you are not able to use the app you are attempting to buy. You may want to consider a newer iPhone. Go to upper black line and click on iPhone to see new choices. If you consider second hand device please take a moment to read these:

Activation Lock for iPhone, iPad, and iPod touch - Apple Support

Also:

The All Too Common SAD Reality of Buying a Used iPad/iPhone

~Katana-San~

Hello ~ If that is the message that you are receiving contact support. Go to upper right hand corner and click on Get Support or:

How to Contact Us - Apple

~Katana-San~