Which artifact is the central Isu device sought by many factions in the first Assassin’s Creed game?

The central Isu artifact sought in the first Assassin’s Creed game is the Apple of Eden.

In Assassin’s Creed lore, Apples of Eden are Pieces of Eden created by the Isu, an advanced civilization that existed before humanity’s recorded history. The devices can influence perception and behavior, making them valuable to both the Templars and the Assassins.

The first game follows Altaïr Ibn-La’Ahad as he pursues targets connected to a particular Apple during the Third Crusade. The artifact’s power helps explain the Templars’ interest in controlling humanity and the Assassins’ opposition to that goal. Later games introduce additional Apples and other Pieces of Eden.

The Apple is not the same object as the Sword, Shroud, or Staff of Eden. Those are separate artifacts in the franchise’s mythology. The word “Apple” can also be confused with ordinary fruit because the series uses a recognizable spherical design, but its fictional function is technological rather than magical.