In the game, the player assumes control of Amicia from a third-person perspective. For the majority of the game, players need to utilize stealth to avoid hostile encounters. Amicia is equipped with a sling which can throw rocks to break drawbridge chains or stun guards long enough for the rats to ambush them, or even kill them with a headshot. The game is a series of survival puzzles, mostly consisting of methods to scare away or distract the hordes of hungry rats in order to gain access to new areas, or direct them towards enemies. The main method of warding rats off is fire, as rats will seldom enter within a radius of burning torches and braziers. Amicia can also craft special ammunition and supplies, which include fire-starting sulfur stones that ignite braziers, stink bombs that attract rats, or fire suppressants to extinguish torches carried by enemies.Amicia's younger brother Hugo can be directed towards specific tasks when Amicia is busy. But be aware of Hugo, he will start to panic if left alone and can attract unwanted attention. Later in the game, the player can assume control of Hugo, who cannot craft items but is able to control rats and sneak through small spaces. All these abilities are combined when the siblings unite in the late game.
