The Game Boy was one of the first handheld game consoles that could play multiple games. It build on the design of the Game and Watch series of handheld games and was an instant success, despite being technologically inferior to its fourth-generation competitors like Sega's Game Gear, Atari's Lynx, and NEC's TurboExpress. An estimated 118.69 million units of the Game Boy and its successor, the Game Boy Colour have been sold worldwide.