Lets say I want to make an app that gives points to users depending on how many countries they visit (using the GPS).
1) Is it possible to actually cheat in this from the phone?
2) Obviously, you can also make someone log in from their phone in their country. Is it possible to bind the phone to the account? Do phones have some kind of unique ID? I want users to be able to change phone, but one phone should only be able to login with the account its bound to.