Game of Thrones: The Board Game ($48) (published by Fantasy Flight Games, allegedly 3-6 players but really 6-6 players*) is based on the classic game Diplomacy, with some of that game's mechanics streamlined and a few layers of thematic chrome added on. It's a perfect fit for a game set in Westeros, as the game forces players to work together toward an unshared victory while providing ample incentives and opportunities to betray each other.
This game is an event that you plan your weekend around; the 2-4 hour playtime printed on the box is laughable. Two sessions (one alcohol-free, the other drink-like-a-Baratheon-no-not-Stannis) with a mix of new and experienced players each ran nine and a half hours, plus an hour and a half or so of teaching beforehand – you could play it as a race against someone in the other room who's binge-watching a season of the show. Both times, however, it felt like about 3 hours of epic conflict (the "Epic Soundtracks" Pandora station helped), and almost everyone playing thoroughly enjoyed themselves.
Why almost? Well, because this is Game of Thrones, and as such terrible things are bound to happen to some of the people involved. It's a game of incredible highs (when you have your opponents pegged and pre-emptively ruin their plans and scatter their troops) and lows (when your lands are being carved up to feed the war machines of your erstwhile allies). If those lows come hard and early, it's going to be a long afternoon.
The basic structure of the game is simple: each player controls the troops of one of the great houses of Westeros in open civil war set around the time of Robert Baratheon's death (there are no overt spoilers for the books or show in the game, though some of the card effects may come close). First player to hold 7 of the board's 20 or so castles wins.
At the start of each of ten rounds, everyone places tokens representing orders to each location on the map that their troops occupy. Then everyone flips the tokens face-up, and the orders (mostly moving, attacking, and disrupting other peoples' orders) are resolved in turn order. At the end of the round, event cards from three decks are turned face-up, which will cause the players to gain troops or resources, cause auctions for turn order and other benefits to happen, and sometimes restrict what players can do in the coming round. Then you do it again until either someone wins or you finish the last round ("Winter is here"), in which case the player holding the most castles wins.
That description leaves out all the richness, though. Everyone starts the game with barely enough troops to credibly hold their own borders on a map that's way too tiny to expand on without bothering your neighbors, and getting more troops is difficult. The combat is designed so that troops neighboring a conflict, no matter who they belong to, can throw their support to one side or the other in a battle at no risk to themselves. So from the very first round, during that token-placing phase you're walking into the other room with the other players to negotiate borders, beg and horse-trade for support in battle, offer temporary alliances, and shamelessly lie to each other. The moment when those tokens flip over and you find out who was lying to you is one of high drama.
In one game I was the Martells, and every turn I had a "yearly summit" with the Greyjoy player, even though my troops never came within 2 provinces of his. We did this both to get a sense of what would be happening on our adversaries' other borders, and to assess the truth of what our neighbors had been telling us. Then I started feeding him false information, and seeing which things I said got back to me through my allies the Tyrells to try to get a read on both their intentions. It paid off when the Tyrells betrayed our alliance – my troops and orders were in place to deal with his attack because I knew he was lying when he told me Tyrell and Greyjoy were going to crush the Lannisters between them that round. This is a game where you play the players as much or more than the pieces on the table.
There's also thematic richness – every area and castle on the board takes its name from the books, and the board is designed to allow many of the iconic moments from A Song of Ice and Fire to play out: The Starks' armies have trouble getting out of the north, Riverrun and Harrenhal are heavily contested, and controlling Blackwater Bay with your navy is a powerful advantage if you want to take or hold King's landing. There are even demands to send resources to help the Night's Watch against the Wildlings, which may or may not cause terrible problems for everyone if unmet, but benefit only the Watch's biggest benefactor if fulfilled.
The combat is thematic as well (and there's not a die roll in sight – you live and die by your own decisions). Each player has a hand of seven cards named for characters in the series that modify the combat value of your troops in battle. The catch is that you have to play all seven cards, one per battle, before you can pick up your discarded hand again, so losing the threat of your strongest card may be worse than just losing the battle they're expecting you to play it in to win. Furthermore, several cards for each house have powers that go beyond their simple numeric value – Cersei Lannister's card, for example, helps the troops not one bit, but disrupts other orders that haven't been resolved yet; and Roose Bolton helps the Starks tremendously, but only when played in a losing fight. When you lose a battle, you might lose a unit or two but usually the bulk of your army is displaced to fight another day, making holding territory difficult and counterattacks near-inevitable. Still, if you can pin down an army with no avenue of retreat they get slaughtered.
Unlike Diplomacy, it's very, very hard to actually knock someone out of the game; but quite possible to make them functionally irrelevant. In our first session, the player in Stannis Baratheon's role (who played it to the hilt; every time someone wronged him he'd pull out a little notebook and silently record his grievances) was reduced by the end to no castles and a single ship; but kept an unwavering hold on the Iron Throne (with its power to decide all ties on his whim) for the entire game.
I ended up apologizing to my real-life neighbor after the game for straight-up lying to his face about where I thought he should send his troops in a sidebar on turn 3; then taking advantage to steamroll through his lands and sink his navy. It took him nearly the whole game to recover to relevance (although he held King's Landing the entire game, the city walls were the limit of his authority); meaning that he spent a good chunk of the 570 minutes we spent playing knowing his actions were mostly fruitless. He said he'd play again, though; and not be nearly as nice next time.
I'm looking forward to it.
* The Feast for Crows expansion, which I have not played, tweaks the rules for a shorter game and is reputed to provide a credible 4-player-only setup using houses Stark, Lannister, Baratheon, and (new to the expansion) Arryn.