A Game of Thrones Catan: Brotherhood of the Watch is based on the classic Settlers of Catan base game. In this game, each area in the Gift supplies one of five resources: lumber, brick, wool, grain, and ore. The barren Ice Fields, however, produce nothing. Players take on the role of Brothers of the Night's Watch and use these resources to strengthen their hold on the north by building roads, settlements, and keeps; recruiting guards for their patrol; or buying development cards. Each of these acts bring players increased power and recognition through the awarding of victory points. The objective will be familiar to players of the original Catan; the first player to achieve ten victory points wins the game and becomes the new Lord Commander of the Night's Watch.

But this is not as easy as it sounds as the area surrounding the Gift can be treacherous. Wildings from north of the Wall have crossed over and follow their own rules of honor, which often conflict with the laws of Westeros. One of their ranks, Tormund Giantsbane, does not respect the Watch's claim to the land as he moves throughout the Gift, robbing resources from the Brothers sent to provide for their Order. While Tormund runs amok south of the Wall, Wildling forces gather in the Frostfangs, awaiting an opportune moment of weakness to breach the Watch's defenses and spread throughout the fruitful lands of Westeros. In addition to building within the Gift, players must strategically balance their resources to defend the Realm from Wildling raiders.