Localizing international game is also a non-trivial task (especially from western to asian markets), but it can easily lead to ten-folding your profits. [2] [3]
[1] https://play.google.com/store/apps/developer?id=Fugo
[2] http://www.gamasutra.com/blogs/HenryFong/20130423/191019/And...
[3] http://www.gamasutra.com/blogs/HenryFong/20130717/196436/Saf...
"As an example Fortumo elaborates there are four times more mobile phones in the world than credit cards and in countries like Brazil, Russia, India and China, credit card ownership is as low as 15%." [1]
One of the best ways (at least for the user) is operator billing, using this the charge is deducted from the user's prepay balance (or added to their postpay bill, but again contracts are uncommon outside Western countries). If they need to buy more Farmville stars they can just go to a shop and top up their phone. Google supports this on a limited number of operators, but even in places like the UK where operator billing is quite mature, they only support it on one. Companies like Fortumo are doing better, but there are still a lot of local payment options missed by this.
As much as companies such as PayPal like to say they are the solution for global payments, the problem isn't solved yet.
[1] http://www.arcticstartup.com/2014/03/25/fortumo-opens-fund-o...
We'll be using it in two of our upcoming games.