As some people above has said Game of thrones is not available in every platform. You cannot find it in Amazon prime (though you can have it by subscribing to HBO go, discussed later) or Netflix.
It available only on hotstar, that too hotstar premium where you can watch it with the world,ie, at the same time as the US premier.
The costs range from Rs.999 per year to RS. 299 per month. So, it's the best way to watch Game of thrones in high definition with subtitles.
You can also get HBO now or HBO go online along with Amazon prime and other online platforms such as Hulu and DirecTv now.
If you want to catch up with the old seasons, you can watch Star world where they are airing Game of thrones at 10pm. I am not sure if it's everyday or alternative days.