Delta Halo (achievement)

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Were you looking for Installation 05, also known as Delta Halo, or the Halo 2 level Delta Halo?
Delta Halo

Delta Halo is an achievement in Halo 2 for Windows Vista, and Halo: The Master Chief Collection. In the PC game it is worth 30 Gamerscore and unlocked by beating Delta Halo on Normal, Heroic, or Legendary. In The Master Chief Collection it is only worth 10 Gamerscore, though it can also be unlocked on Easy.

In the PC game, it is represented by the head of an Orbital Drop Shock Trooper. In The Master Chief Collection it is represented by a screenshot of Installation 05.