This isn't really a walkthrough, so I didn't want to give it that title. Just a heads up, in every mission past 7 you will need to use the Arctic Warfare sniper rifle. I was really confused by this because I was using M24 and nothing seemed to be happening when I shot things. This might be a glitch in the game, but If you find that you can't shoot anything after getting to level 7, switch to the AW.
