Long, long ago, there was Nu, the name given to the dark, swirling chaos from which all life sprang. Eventually, from this chaos there came light, the sun; the creator of life. The Egyptians thought the sun was a god, and called him by different names. At midday, when the sun is at the height of its power, it was called Ra, which means great and strong. In the evening, however, when the sun set, it was known as Atum, the old man. Lonely and alone in the world, Ra joined with his shadow to produce a son and a daughter. He gave birth to his son by spitting him out, and he named him Shu, god of the air. The Sun then vomited and spewed up his daughter, Tefnut, and made her goddess of rain, mist and moisture.
Shu and Tefnut were given the task of putting chaos into order, and started by separating the light from darkness, but while doing this, they got lost in the watery chaos of Nu. The Sun was terribly worried by the disappearance of his beloved children. He took his one eye and sent it out into the universe to search for them. When they finally returned, the sun god was so overcome with joy that he wept tears of happiness. His tears poured down upon the earth and wherever they fell humankind sprang up. The Sun and his children then decided to make another eye, and this became the moon. The sun god was now ready to create a world for his new people to live in. Shu and Tefnut produced twins who were tangled together at birth – Geb, the earth, and Nut, the sky. In time, Geb and Nut produced four children, two gods and two goddesses, who represent the four forces of life: Osiris, god of fertility; Isis, the mother goddess; Set, god of evil; and Nephthys, goddess of death.
The brothers Set and Osiris are in a near constant battle for the throne of Egypt. It started with a legal judgement before the Ennead, a group of Egyptian deities who would decide who was worthy of inheriting the kingship. Set (who is also often depicted as the god of foreigners) acts as a usurper, stealing the throne and murdering a mutilating Osiris. Isis, Osiris' sister-wife (yeah, that's a thing in ancient Egypt) cries over her dead husband-brother, and her tears create the Nile River. But then Isis reassembles his corps and resurrects Osiris with the help of Nephthys. The resurrection lasted long enough to conceive his son and heir, Horus (god of war and the sky). Horus sought revenge upon Set and many of the ancient Egyptian myths describe their conflicts.
The Flood
One day, Ra grew angry because humans had become disrespectful, and he believed they were plotting against him. Ra calls on the other gods to ask them how he should deal with the ungrateful "children" of his Eye. Ra sends the goddess Sekhmet to destroy part of humanity for their disrespect and unfaithfulness. But Sekhmet goes too far and goes on a bloody rampage that threatens to destroy all of humanity. To stop her, the other gods overturned massive jugs or red wine to create a great flood of what would look like blood, which Sekhmet would devour. Thus, Sekhmet got drunk of the wine and passed out, ending the slaughter and saving humanity. This event was commemorated by the Egyptians in a wine drinking festival during the annual Nile flood.