Instructions
Play any mode in "Halo: Reach" to earn credits by killing enemies, completing matches and completing challenges. Matchmaking multiplayer usually gives the highest amount of credits over time. Forge maps usually give the lowest amount of credits over time.
Earn 450,000 total credits to reach the rank of "Lt. Colonel." Your rank is dependent on how many credits you have earned, not the amount you currently possess. Save at least 130,000 credits.
Press "Start" to open the menu.
Choose "Armory." Select "Helmets."
Purchase the MJOLNIR Mark V helmet, if you want Master Chief John-117's helmet from "Halo: Combat Evolved." It costs 130,000 credits.
Earn 950,000 additional credits, for a total of 1,400,000 credits, to reach the rank of "Brigadier." Save at least 300,000 credits.
Purchase the MJOLNIR Mark VI helmet from the armory, if you want Master Chief John-117's helmet from "Halo 2" and "Halo 3." It costs 300,000 credits.