play through to that part of the game. you have to get to that point in the campain before you can start off there.
DUMB
i think halo 2 multyplayer
No, in Halo 2 you can not unlock armor.
Mabye map packs
yes you can well in multiplayer anyway
no
Unlock what head?
You can't, its an Xbox 360 exclusive.
not really sure but it might be to unlock guns
you hav 2 complete the game
they unlock halo timelines
There is two ways to get it #1 unlock all of the armor #2 is to become the highest rank in halo reach
Unlock Halo 3:ODST's Campaign Complete Achievement. Once you beat the ODST campaign, visit Halo Waypoint on the dashboard to unlock the item.