The First Templar follows the journey of French templar Celian of Aristide as he searches for the Holy Grail, entangled in a web of plot twists including a Saracen invasion and a conspiracy against the templar order. His mission is not just to find the Grail but also to protect his people.
The game is designed for co-op play, where the protagonist Celian fights alongside a companion, mostly his daughter Marie, with the player's ability to switch between characters only necessary during specific puzzles. The gameplay features melee fights against multiple enemies, trap courses, and stealth sections, with a focus on switching between three moves: standard attack, blocking, and a special attack that depletes "fervor" energy.
Each level has a main objective and three bonus missions, offering rewards such as experience points and equipment parts. These are used to upgrade Celian's abilities and unlock new moves, while the equipment provides improved armor and weapons.