It's Christmas time in New York City and a strange virus has appeared turning seemingly normal citizens into the insane, violent Infected. Rookie Officer Stevens is one of the first victims but unlike others, is strangely immune. The mysterious Dr. Schaeffer discovers that Stevens' blood can be used to destroy the otherwise invincible Infected, and creates a special "viral gun" that fills shells with blood from Stevens' arm and blasts them straight into the Infected, causing them to violently explode. Featuring an engrossing single-player campaign with lavishly gory details, Infected unlocks the world of Wi-Fi via exciting multiplayer modes. To participate in multiplayer combat, players create their own character or avatar. Those who are victorious in combat can "infect" the loser's PSP system with their avatar and gain ranking points. Avatars can be defeated through a variety of methods, as well as passed along from player to player thus creating a viral chain letter of attack.