Campaign Complete: Heroic (Halo 3 achievement)

Campaign Complete: Heroic is a Halo 3 Campaign Achievement. It is earned when the player completes the Halo 3 Campaign on Heroic difficulty. This Achievement gives 125 Gamerscore to the player and unlocks the Campaign Complete: Normal achievement if not yet earned. It can be earned through either co-op, single player or a combination of the two.

It is represented by a shield with the Marathon symbol on it with two crossed Combat Knives.

This achievement unlocks the Flight Harness helmet for Elites.

Tips
One way to achieve this is to complete campaign on normal, which will allow you to grow comfortable with the button layout and the new systems. Tactics become a necessity, as well as weapon familiarity. While it is not as difficult as Legendary, it is certainly more difficult than Normal. Do not get discouraged, perseverance and dogged determination will serve you well in completing the campaign on Heroic.