So, I was browsing the Xbox Live Arcade, and then I found this game that is free. It's called Doritos Dash of Destruction, and it is free. The size is around 60 MB. Once you download it, there are two campaign modes. In one, you are a T-Rex chasing down cars with Doritos and eating them. In the other, you are a delivery truck who delivers doritos. All you have to do is spend ~30 mins and then you should have 190 Gamerscore. The reason that it is not 200 Gamerscore is because the last 10 GS is to win a multiplayer game, and no one plays. However, my gamertag is k7vin11 and if oyu send me a game invite, I will let you win just so that you can get that achievement.
