Summon Night: Swordcraft Story progresses through the story on a day-by-day basis. The entire game consists of 10 days, where the player traverses through the town of Wystern and the Labyrinth Dungeon. Each day, more levels of the Labyrinth are unlocked and the player is required to travel deeper to complete mandatory quests. A day normally ends after a tournament or boss battle. During the night, the player can choose who to spend the night with, which will control the following cut-scene.
Apart from the story quests, there are multiple side-quests, offered by re-occurring NPCs. The rewards of these quests are usually enchanted weapon techniques. Often, they are simple fetch quests.
One of the main focuses of the game is to forge weapons for fighting. To forge a weapon, the player needs the weapon technique and the materials to create it. Refer to the crafting guide for a more in-depth tutorial on this process.
Battles in Summon Night take place inside dungeons. They are initiated as random encounters. On the battle scene, the player will be placed into a small side-scrolling area with one to four opponents. They are able to walk, run, jump, guard, attack, summon their guardian beast and use items. Up to three weapons can be equipped, and up to four different items and spells can be placed onto the guardian beast. This must be set up before a battle begins. If no weapon is available or equipped, the player will be forced to battle with a hammer. During the battle, the player can switch freely between their equipped weapons and use any of the selected items and spells. A battle is won when all opponents have either fled or have been defeated.
The character has three statistics which determine his or her ability to fight. Strength controls the amount of damage they inflict. Defense controls the amount of damage opponents will inflict. Agility controls speed while moving, and jumping height. These stats can be increased by equipment or leveling up. The game also uses a health point system, which will be increased automatically upon level up. Hit points are also gained in varying amounts depending on which stats were selected to increase.
Each weapon also has a score akin to hit points, called duration. Each attack will decrease the duration of the weapon very slightly. If duration of a weapon hits zero, the weapon will break and will no longer be usable. When a weapon breaks, it leaves behind a weapon shard and cannot be restored. Duration is refilled after every battle. The rate which a weapon's duration decreases is proportional to the weapon's TEC score. TEC can be increased by fighting with the weapon more often.