The best board games receive awards. Settlers of Catan received Germany’s Spiel des Jahres (Game of the Year) award. This is one of the highest honors a board game can receive. The game also received the Deutscher Spiele Preis (Award for Best Adult and Family Games) and Essener Feder (Award for Best Rulebook).  These awards prove the game's success and international recognition. Successful board games prove their popularity. As an internationally recognized board game, Settlers of Catan is popular. Millennials’ interest in board games has increased, especially German-style board games such as Settlers of Catan. Therefore, Settlers of Catan is popular among millennials.
A board game's awards do not necessarily prove that the game is popular. It could have received awards because judges admired the game's sophistication and design, even if it was not a hit with audiences. Additionally, these awards are for various categories unrelated to millennials. They might be more interested in niche board games that do not have any awards or are nationally recognized. We should not define millennials' enjoyment of a board game by the number of awards it holds.
[P1] Internationally recognized board games are popular. [P2] Settlers of Catan has been internationally recognized. [P3] Therefore, Settlers of Catan is popular among millennials.