No and there never will be. The idea of Zombies in a Halo game already exists, Infection and the flood. The possibility of being able to play as the flood in a future Halo game is not impossible, though.
Of course. On costume games the call it Infection. It's really cool. You can customize the setting and stuff it's so tight.
No, not without mods.
no
There are no cheat codes for Halo, only mods.
No there is not a mod
there might be now because there is a new campaign on halo 3
no, all there is not any flood in halo 3 odst firefight
depends on what you're looking for. but most good mods in halo require a jtag. but a good site to look up mods is- http://www.thetechgame.com/
Mods.... search halo armour oblivion
You can in HALO 1 if you use mods, but it has to be on the computer.
As of now the Halo: Reach beta is gone, your not going to be able to.
Yes. There are a lot of mods for Halo and Halo Trail on PC.
See halomaps.org for mods like sonic for halo. It is only for Halo Custom Edition, but you can convert it to Trial or Retail with Pearl or Demo with Queene Anne's Revenge.