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Call of Duty Modern Warfare 3 review"The Spec Ops mode returns here too, in the form of Survival and Missions. Survival is a kind of Horde mode; waves of enemies roll up, each throwing something new into the mix, and weapons and support can be purchased either between waves or during a firefight. It's fast-paced, well conceived cooperative gameplay (although you can also play it alone) and Survival is divided up into four sets of four missions, with each set having a different theme in terms of enemy types."