Amazon is a online store that has great game deals and offers. Amazon digital games available only to customers located in the United States and who have a U.S. billing address. But still you can purchase digital games from amazon even you reside outside US. Only you need a US billing address and a credit/debit card that can use to make online payment. Amazon doesn't accept paypal or any other similar service.
Step by step guide to purchase :-
# Register at Amazon. Use a VPN to change your IP Address to USA. (Optional)
# Add your credit/debit card. Use a USA billing address. If you don't have one contact me. I'll give you one.
# Now you can purchase any game you want. ( Please note that you only received a product key (cd-key) when you purchase digital games. )
# After you purchase go to Games and Software Library and copy the product key (cd-key).
# Sing In to official game client that support the game you purchased. (Ex: Battlefield 3 - Origin). Go to Redeem Product Code, enter product code there and redeem your game.
# After that your game will be available to download through the game client.
All done, Lets Play !