Announced today on Reddit by u/blackninja9939 the Game of Thrones Mod for Crusader Kings two is now available for download as a complete overhaul mod.
The mod will allow players to enter into Westeros and play as either one of the families, a dothraki horde or even the free cities of Essos.
On a personal note Crusader Kings 2 seems like the perfect game for the Game of Thrones series. The vassal system in Crusaders Kings seems comparable to the ones in the game and Westeros can almost be compared to a version of the Holy Roman Empire in the high middle ages. Also if you consider that the world is so similar to the middle ages of Western Europe than Crusader Kings might be the best game that captures the world of Game of Thrones.
You can read the entire update list for the mod on reddit here.