This is different from the others; it's cool.

I know that your Bundle Identifier needs to match your iTunes Connect's version. I know you need to make a new AppleID through your dev app and not through Game Center. Most people get this fixed when they force quit their app and game center and launch theirs first.

I am not one of those people.

If I take the GKTapper tutorial and use my game's Bundle Identifier as the only change, things are good. On launch, it asks me if I want to use an existing or make a new account. But more importantly, it says * Sandbox *. (Before I log in, mind you; this is not an account problem at all.) Once inside I can see my achievements.

If I load my game, I has a sad. On launch I get the same dialog, but it does not say Sandbox. My game is two weeks away from being done after many long months. Moving everything in to a new project is possible, but a pain. So the question is:

What magic setting does GKTapper or a new project have that my game that I started in June does not that lets you get to Game Center's Sandbox?