Gears of War 3 is rumored to have underwater levels in a heavy mech suit, upgraded weapons, new mutated Locust, and to be based on Vectes Island. Cliff Bleszinski officially announced Gears of War 3 on Late Night Jimmy Fallon on NBC.
From the article in EDGE magizine, Gears of War 3 is to show a debut trailer April 12th, gameplay footage in June, and the release of the game to be in April 2011. Gears of War 3 is an upcoming and the final game in the Gears Trilogy for the Xbox 360.
