@itshammad
The game is not available on discs as mentioned by another member above and is only available to download from Xbox LIVE by using Microsoft points. If you want to download the game, create an Xbox LIVE profile and buy the appropriate number of MS points required to download the game.
To buy Microsoft points, visit PG's own online store or create a thread in the marketplace section demanding the MS points. There are lots of people here who will be willing to help you out, thank you.