If you get an error message when you try to sign up about Challengermode not being available in your country, this is because we are not open in that region yet. This can be due to certain regulatory requirements in that country or because we haven't seen enough of a demand from the country yet.
We are constantly expanding to more regions and countries, so the best way to stay up to date about when we will be in your country is to follow us on Facebook or Twitter where we will make announcements about stuff like that.
Running into other issues, or do you have additional questions? Feel free to chat with us by clicking (?) on Challengermode.