One of the significant new additions to the next installment in the Gears of War series -- Gears of War: Judgment -- is the OverRun mode, which focuses on competition and pits Locust and COG soldiers against each other. If you're keen to take a peek at it, the video below walks you through the finer details, courtesy of the series' own Damon Baird.
The short version is it's a 5v5 class-based multiplayer mode. It appears somewhat traditional, but does feature a twist or two. For instance, you play as both attackers and defenders in each match.