It is were everyone goes red except one person. The remaining person goes green. The starting weapons should be a sword and a hand-gun. The weapons on the map should be shotguns. There is no radar. The red people(humans) are only allowed to use guns. The green people(zombies) are only allowed to use swords. If a green person kills a red person that person must joiin the zombie's team. The last human player is the winner.
It is like the zombies have an infectous bite of death.
My gammer tag is Reaper02235

Do you download this game cause I got halo 2 and I can,t find a game called humans v.s zombies

It's not a game type that's included in the game nor can you download it. Players have to follow the rules manually. Maybe they'll add this in Halo 3 - who knows...