Halo: Reach: Find the hidden binary signature.
Halo 2: Beat the par time on High Charity.
Halo 3: Find and claim the Iron Skull.
Halo CE: Activate Terminal 1 on The Pillar of Autumn.
Halo 4: Survive Spartan Miller (Ep.5 Ch.1) of Spartan Ops on Heroic or Legendary.
Halo CE: Complete The Library on Heroic or Legendary difficulty without dying.
Halo CE: Find and claim the Malfunction skull in remastered mode.