Adjudicate The Arbiter

Adjudicate The Arbiter is an Achievement in Halo Wars and Halo Wars: Definitive Edition that is unlocked when the player completes the campaign on the Heroic difficulty.

It is worth 30 Gamerscore in both games.

Trivia

 * The achievement seems to be a judge's gavel hitting the Arbiter's head.
 * To adjudicate means to judge, or come to a verdict, hence the presence of the gavel. An arbiter (or arbitrator), adjudicator, and judge all serve similar roles.