Machi Koro: Harbor Expansion, a.k.a. Machi Koro Plus, expands the Machi Koro base game by adding thirteen new types of cards: ten new establishments, one new starting establishment, and two new landmarks. The expansion adds more complexity to the game, including seaports and airports that can be upgraded with additional boats (in the case of seaports) or facilities. Players also now need to complete six landmarks instead of four. Players will now shuffle all the establishments together and randomly create a market of ten cards which are available to purchase at any time.

Machi Koro: Harbor Expansion includes cards that allow for up to five players to compete at the same time (82 cards total), while Machi Koro Plus includes only the new types of cards (68 cards).