As you fight your way through the alien infested wilderness of the Galuga archipelago, an earthquake unexpectedly erupts. You stay on your feet, shooting down brainwashed Human soldiers of the Red Falcon army while jumping over the ridges and trenches opening up erratically on the ground. As the soil beneath your feet finally calms down, you find yourself near a suspicious door, possibly the entrance of the enemy base. Suddenly, the ground begins shaking again as a massive structure emerges up from under the ground. A sensor fortress wall!