Infection

Infection is a confirmed multiplayer gametype in Halo 3, discovered by beta source code hackers. It has been hypothesized that there is the Zombie team fighting against the Human team. The object for the humans is to survive the Zombie infection--a variation on the multiplayer game Zombies, but enforced by rules instead of the honor system.

The Zombie gametype pits a "zombie" or "infection" team against the "human" team. The goal of the human team is to survive to a time limit; the goal of the infection teams is to infect the humans, who respawn as members of the Zombie team. A second theory is that the players are pitted against a "team" of Flood AI. Given the 360's power, and Bungie's drive to set the multiplayer bar, this seems a possibility. Other details are so far the subject of rumor.

Possibilities

 * Instead of the Flood being AI, the players could BE the Flood. This is very, very unlikely however.

Although, there is a chance it could be similar to the Infection mode found in Perfect Dark Zero.