The Game of Thrones board game from Fantasy Flight is my favorite story-to-game crossover ever. It perfectly captures the dubious loyalties and shifting alliances of the novels — players need to negotiate and form alliances to win, but only one can ultimately come out on top. All actions are done with secret order tokens, allowing for lots of fun misdirection and betrayals.
The original game includes Starks, Tyrells, Lannisters, Greyjoy, Martell, and Baratheon. The new expansion brings in the Targaryens and the House of Arryn, along with a sideboard for Essos. It also brings in the Iron Bank and even better, a vassal system for unchosen factions. The vassal system sounds great, since you often can’t get 8 people together for a game. 🙂