Islebound: Emerald Edition is a special edition of the game with some altered components and rules. It's best to think of it as a variant of the game, rather than a 2nd edition. This edition removes the book resource from the original game and replaces it with emeralds. Emeralds have different uses than books. You collect them when visiting a player-owned town and when you taking over a town. Emeralds must be used to buy building cards, and they can also be used to perform special abilities, such as keeping pirates and serpents after combat!