Ys IX: Monstrum Nox is an action role-playing game played from a third-person perspective. It further builds on the gameplay foundation of Ys VIII: Lacrimosa of Dana, where players control multiple main characters that can be switched between on-the-fly, each with their own play styles and unique skills. Players collect a variety of weapons and items by defeating enemies and opening chests.
Players can consume SP to unleash a character’s unique skill attack, and SP can be restored by landing hits on enemies or it can regenerate faster when the player is not attacking. Boost mode, a returning game mechanic from Ys: The Oath in Felghana and Ys Origin, temporarily increases damage dealt, decreases damage received, and increases attack and movement speeds.
New to Ys IX, each party member has traversal abilities, called Monstrum Gifts, such as gliding and running up walls. Players can reach various places and locate hidden secrets in the city of Balduq and dungeons by utilizing these actions.