...must have an address in the country of the currency you use...
That also doesn't make any sense. I use my US-based USD credit card in Canada to buy things all the time, including online, including other subscriptions, and have no issues with my billing address being in a different country and a card being in another currency than the Canadian address I'm having my items shipped to/service provided to. An online-only multi-country/region service like a game subscription should be equipped to deal with this kind of thing even better.