The local co-op feature allows two players to play Ys IX: Monstrum Nox together, at every point in the story where more than one character is available.

Once this setting is enabled, the co-op player can drop in and out of the game using the “Start” (or equivalent) button on any non-primary controller, while the “Select” button on the secondary controller toggles the player ID indicators (“P1” and “P2”) on and off.

Unlike Ys VIII: Lacrimosa of Dana, where co-op was mostly limited to combat, the second player is largely equivalent to the primary player in terms of capabilities in Ys IX: Monstrum Nox, including movement and combat abilities, using Monstrum Gifts, discovering and triggering landmarks, enemies and events, opening chests, picking up collectibles, and initiating dialogue.

Another significant improvement over the co-op feature in Ys VIII: Lacrimosa of Dana is that character switching is implemented individually for each player: that is, if there are three characters in the current party, players one and two can both independently switch to the currently-unused character without affecting each other.

We have completed 100 percent of the game in co-op at Nightmare difficulty during testing, and I personally think that it is an incredibly enjoyable way to experience Ys IX: Monstrum Nox.