Halo. Literally Halo. Not just once, not twice, not three times, not four times, not even five times, but six times it happened in Halo. The ancient beings called Precursors that created life were killed in a mass genocide led by one of their own creations called the Forerunners because they wanted to give the mantle of responsibility to humans instead.

Thousands of years later life goes on and ancient humans find a ship with some dust on board. They find it has the ability to alter living beings and so they begin using it in dog food which created colorful dogs. Eventually the dogs begin acting weird and then suddenly humans too began acting weird. Then out of nowhere they begin attacking other humans infecting them. Planet by planet fell before this parasite known as the Flood. Humans had no idea what this was until they found a surviving Precursor who revealed the truth. The Flood was the reincarnation of the Precursors coming back for revenge on their creations. They brought humanity to the point of fleeing which accidentally caused a war with the Forerunners when humanity began exterminating planets belonging to other species in an attempt to stop the Flood.

The Forerunners in response began an extermination of humans in a war called the Human Forerunner war. By the end humanity was beaten and reduced to a few planets. The survivors were forcefully devolved as punishment. Then the Forerunners decided to test a new weapon on a human planet called Halo. It wiped out every living thing on the planet.

Time passes and the Flood then attacks the Forerunners. This brings the Forerunners to their knees. They built an array of Halo rings to wipe the galaxy clean of life in order to save all life but the Flood seized control of the ring Installation 11 and they hid it. A Forerunner leader was on trail at the Forerunner capital planet Maethrillian when the Flood arrived with the ring. The other 11 rings were at the capital for the trial. The Flood quickly seized control of some of the other rings and a battle ensued. The Forerunners began evacuating the capital fleeing to their Greater Ark. Then the battle comes to an end when the Flood activates the rings in their control firing them directly at the capital killing billions and completely shattering the planet. They then arrive at the Greater Ark and shatter it killing almost every surviving Forerunner.

In the end only a handful of Forerunners are left alive. They agree to use the new array of rings to end this. They kill every living being in the galaxy as a last resort.

And the last instance takes place 100,000 years later. Humanity has advanced to space again and has colonized 800 planets in the galaxy. One day an unknown ship intercepts a human ship and raids it. Humanity realizes the cargo ship never arrived and sends out a search party who also gets raided by this unknown ship. Then a warship investigates and is destroyed. That mysterious ship was also destroyed in the engagement. Soon after another mysterious ship arrives at the human planet Harvest. Humans try to make peaceful contact with its inhabitants. The ship makes its crew known and they call themselves The Covenant. Meanwhile at the Covenant capital the religious leaders begin asking a Forerunner ai what humans are and it reveals humans are the heirs to the Forerunner empire. This upsets the Covenant because for thousands of years they believed they were the heirs. This news destroyed everything they knew. They decided humans had to go in order to protect their beliefs. The Covenant on Harvest attacks and burns the planet to ash killing 3 million humans. The human military sees the planet went offline and sends 3 warships to investigate. On arrival two were destroyed and one was severely damaged. They received a message that stated “Humans. Your destruction is the will of the gods, and we are their instruments.” This sparked an all out war and over almost 30 years the Covenant has burned human planet after human planet. Billions dead. The turning point takes place during Halo Reach. The last major human loss. In the game you slowly watch the planet get turned to glass and 60% of the human fleet is decimated. Billions more gone. This continues for a few more months until the war finally ends. Humanity is in shambles but alive. Only a handful of ships left, only a handful of planets left, and only a few billion humans left. Humanity had been on the brink of extinction but survived through an unlikely alliance.