The game's single-player campaign is designed to allow individual players to progress through the missions in the order they prefer. Enemy squads are likely to have learned a few new tricks as well. Computer-controlled teammates act and react individually, and the game's contextual 'battle chatter' system lets players know exactly what's on their minds. The sequel boasts graphical enhancements and significant improvements to artificial intelligence. This Infinity Ward follow-up to 2003's critically acclaimed Call of Duty pushes farther across the European Theatre of World War II, with missions spanning the desert fighting in North Africa to the tank assaults on the Russian front.