Today a multinational video game developer, Sega was the first to break Nintendo's grip on the gaming industry, expanding from primarily an arcade game company to become the dominant game console manufacturer in North America. A major part of that success came from the hard work and innovation of its subsidiary, Sega of America, who in a little more than a decade wrested the majority market share from Nintendo and revolutionized how games were made. Drawing on interviews with nearly 100 Sega alumni, this book traces the development of the company, revealing previously undocumented areas of game-making history, including Sega's relationship with Tonka, the creation of its internal studios, and major breakthroughs like the Sega Channel and HEAT Network. More than 40 of the company's most influential games are explored in detail.