Epic Games presented the first trailer for Gears of War 3's single-player campaign tonight. It sets up the storyline and also teases some fun bits from the campaign.

In Gears 3, humanity is at the brink of extinction. The few remaining survivors are fighting a two front war against the Locust Horde as well as a race of mutated Locust known as the Lambent. Marcus Fenix receives a transmission from his father, a prominent scientist who went missing years earlier. Marcus and his squad head out to find Adam, who claims to know how to stop the Locust once and for all.

There are a lot of cool flashes of gameplay throughout the trailer. At one point, we get to see a battle between COG and an enormous Lambent monster. It also looks like there's going to be at least one underwater level in the game; the trailer seems to show the player piloting some kind of submersible.

GoW3 will be released on September 20th in North America and on the 22nd in Europe.