It exposed Halo not as a benevolent tool of protection, but as ruthless and genocidal as the Flood themselves.

The Flood’s sudden ambush was not just an effective use of horror when the first Halo game came out, it also subverted player expectations and added to a grayer area to the military conflicts that dominate its story. It's this event that leads to the Flood being freed for the first time in centuries, quickly spreading across the eponymous Halo Ring - which is revealed to be designed for exterminating the Flood by starving them of sustainable life sources. In the first Halo game, the Flood were completely hidden until Master Chief finds a recording of one marine’s experience. Because of these powers, the Flood are considered one of the biggest existential threats in the Halo universe.ĭespite being one of the most memorable aspects of Halo and its world thanks to their various forms, the Flood’s existence used to be a spoiler. Another consistent aspect of the Flood is its ability to retain a host’s memories, essentially becoming a distorted version of their host’s character. The Flood did not take sides during the Human-Covenant war, assimilating everyone and every thing possible. This variety is especially blatant when a human-based Flood is compared to a Covenant-based Flood. While their skin color is relatively consistent, ranging from green, to black, to brown, their height and weight depends on their host. Because of their flexibility, the Flood’s physical appearances can vary.

By the time the events of Halo: Combat Evolved took place, the Flood had already assimilated most lifeforms in the galaxy into their hivemind. They are a highly adaptable parasitic species that reproduces by consuming both the bodies and minds of sentient lifeforms. The Flood are conceptually nightmare fuel in the realm of science-fiction. Although the Flood ended up targeting the Milky Way, their initial attacks wound up benefitting humans at the expense of Forerunners. They became the Flood and destroyed the Forerunners, taking over Forerunner-controlled planets in the process. The remaining Precursors assimilated into this newfound corruption. Some Precursors, who lost the war, were turned into regenerative dust that created horrific mutations.

According to Halo lore, the Flood is a product of a war between the Forerunners and the Precursors.

Sudden attack gameplay