Yes, it is possible to play Sniper 3D outside of America as long as you have a US iTunes account. However, there are some limitations to this. You won't be able to log in to their official website with a non-US Apple ID, and if the app store server detects that you're not from the US.
It will automatically redirect you to a different page with no real link to download the game. In order to avoid those obstacles, just follow the steps below on how to download Sniper 3D with or without a jailbreak.