Firefight: Windward

From Halopedia, the Halo wiki

Firefight: Windward

Firefight: Windward is an achievement in Halo 3: ODST awarded for scoring over 200,000 points during a match of Firefight on the map Windward. It is worth 10 Gamerscore.

This achievement is represented by an olive square with a bird of prey flanked by a star on each side.

When doing this on single player, allow a minimum of 2 hours to reach the 200,000 points[1].