Upon his ascension as pharaoh, Tutankhamun inherited his father's Apple of Eden, known to him as "the Aten"; the focus of Akhenaten's monotheistic religious worship, and a physical manifestation, of Aten.
Instead of continuing his father's monotheistic beliefs, Tutankhamun instead decided to restore the old Egyptian gods to prominence and passed the artifact to the priests of Amun, entrusting them to use it so as to maintain Ma'at; order and justice for the Egyptian people. After his death, Tutankhamun's spirit subsequently inhabited the Duat.
In 38 BCE, Tutunkhamun's spirit, alongside those of his parents and the Great Pharaoh Ramesses II were seemingly returned to the world of the living by the God's Wife of Amun, Isidora, who had possession of the Aten.
Now residing in the Duat, an aspect of the Egyptian afterlife, Tutankhamun was confronted by the Hidden One Bayek of Siwa, who managed to gain access to the Duat through a portal connected to the pharaoh's tomb.
Behind the scenes
Tutankhamun owned an iron dagger made from a meteorite.
The full translation of Tutankhamun's name is Nesu bity (NebkheperuRa) Sa Ra (Tutankhamun), which reads in English as "King of Upper and Lower Egypt (The lordly manifestations of Ra) Son of Ra (The living image of Amun)." Prior to his ascension to the throne Tutankhamun's name was Tutankhaten "(The living image of Aten)," in-line with his father's monotheistic worship of Aten.
Although he is portrayed as being significantly taller than Bayek and powerful, the real Tutankhamun was a physically disabled teenager with a spindly build.