A Gears of War team known as Tac-Com recently discovered an interesting Easter egg in the form of a Duck Hunt style of minigame. The game launches enemies from the ground, and the more you kill the better your reward. The secret is found by shooting three coins which are hidden in trees throughout the level in a specific order. Once all three have been activated, a secret room is revealed. In this small area, a total of five aliens will jump from underground in random succession, prompting you to shoot them out of the air. If you manage to kill all five, you are rewarded with Mulchers, a heavy gatling gun style weapon.
Head past the jump to check out Tac-Com's video.