Gameplay

 Fire Emblem: Three Houses is a tactical role-playing game in which players control a player character whose gender and name are chosen at the beginning of the game. During the opening hours, the player character is asked to teach at the Garreg Mach Monastery, which acts as a hub for game activities. Choosing a particular house to teach impacts the narrative from that point on. The player's time is divided between story-based battles that advance the main narrative, and periods in Garreg Mach where they interact with students and staff members there. While the opening half of the game focuses on this school system, the story skips ahead five years and focuses more on battle, with the player being locked to the house they chose during the opening half.

During the periods between storyline battles, the player has a set number of days marked on a calendar, which can be used for a variety of activities from teaching classes and field exercises to planting seeds in the greenhouse and fishing in the pond. The player also has free time events, where they can socially interact with students and build up relationships with them. Building a relationship is done through Support actions, with actions and dialogue choices impacting a character's Support level. If the relationship is strong enough, this can lead to the two marrying after a story-based time skip event. By raising particular attributes through actions in battle and within the Monastery, the player can recruit students from other houses, alongside other characters. Each action during academy sections costs a fixed number of time points, with a set number of time points available each day and more activities than can be covered by the points available. The player must choose which events to trigger, losing access to others in consequence. Network play and Amiibo functionality are also supported, with network play allowing players to passively visit other players' monasteries online, and compatible Amiibo figures to be scanned for additional materials and bonus music tracks for scanning Fire Emblem-specific Amiibo.

As with other Fire Emblem games, Three Houses uses a turn-based battle system; players take control of a set number of unique units. They move across a grid, transitioning from a top-down perspective to a third-person view when a battle is triggered. A new feature to the series allows player to hire Battalions, additional troops that can support a chosen unit. Battalions have passive abilities which grant character buffs to the lead unit, and can perform special moves called Gambits, which can range from healing multiple units to stunning powerful enemies. Players can also zoom in on the battlefield to assess individual battalions. As with other entries, there is a "Classic" mode where characters who fall in battle are subjected to permanent death, and a "Casual" mode where fallen characters are revived after each battle. After a certain point in the story, players can rewind and undo a set amount of turn actions per battle using the "Divine Pulse" ability.

Every unit is assigned a character class, which can be customized. While characters have starting abilities which naturally grant them a class, they can be taught additional skills which alter their class. Class changes are available upon a student's "certification" during the school segments, with certain prerequisites recommended to have a higher chance at passing the corresponding certification exam. Prior to starting a school week, lesson plans can be put into place to individually manage a unit's growth, build Support between two classmates by engaging them in group assignments, or simply instruct the class automatically with a passive "auto-instruct" feature. Rather than the previously-established Weapon Triangle of earlier Fire Emblem games, different units have weapon-based skills called Combat Arts they can be taught during the school segments. Weapons have a set number of uses before they degrade and have their stats reduced. Combat Arts are learned by becoming proficient in a type of weapon. They deal higher damage than standard attacks in exchange for a large chunk of a weapon's durability.