Call of Duty: Modern Warfare 2 is introducing Invasion mode to its online multiplayer suite, and fans of the classic Ground War mode with large-scale maps and teams will be happy to see it. On top of that, fans of Titanfall's Attrition mode will have something to look forward to in Call of Duty this year, as human teams in Invasion will be supplemented by a host of AI teammates and opponents to make maps feel full and chaotic.