Big Boss, a former CIA agent and mercenary, works to stop a rogue military group from launching a nuclear war. As the main character Snake, he tracks down a walking tank called Peace Walker that has nuclear launch capabilities. After defeating Peace Walker in combat, Snake is able to prevent a global nuclear crisis. The game was well received, winning several awards for its story, gameplay, and visuals on the PSP. It sold over 1.5 million copies and generated $20 million in revenue.