The Game Boy is an 8-bit fourth generation handheld game console developed and manufactured by Nintendo. It was first released in Japan on April 21, 1989, in North America later the same year, and in Europe in late 1990. It was designed by the same team that developed the Game & Watch series of handheld electronic games and several Nintendo Entertainment System (NES) games: Satoru Okada, Gunpei Yokoi, and Nintendo Research & Development 1. It is Nintendo's second handheld game console and combines features from both the Game & Watch handheld and NES home system. The console features a dot-matrix screen with adjustable contrast dial, five game control buttons (a directional pad, two game buttons, and "START" and "SELECT"), a single speaker with adjustable volume dial and, like its rivals, uses cartridges as physical media for games. The color scheme is made from two tones of grey with accents of black, blue, and dark magenta. All the corners of the portrait-oriented rectangular unit are softly rounded, except for the bottom right, which is curved. At launch, it was sold either as a standalone unit, or bundled with one of several games, among them Super Mario Land and Tetris. Several accessories were also developed, including a carrying pouch, a camera, and a printer. The Game Boy received mixed reviews from critics and was deemed technologically inferior to its fourth-generation competitors (Sega's Game Gear, Atari's Lynx, and NEC's TurboExpress). Its lack of a backlight, graphics, bulky design and price were met with criticism, but it also received praise for its battery life, library of games and durability in its construction. It quickly outsold the competition, selling one million units in the United States within a few weeks. An estimated 118.69 million units of the Game Boy and its successor, the Game Boy Color, have been sold worldwide, making it the fourth best-selling video game console of all time. It is one of the most recognizable devices from the 1990s, becoming a cultural icon in the years following its release. Several redesigns were released during the console's lifetime, including the Game Boy Pocket in 1996 and the Game Boy Light in 1998 (Japan only). Production of the Game Boy continued until 2003, well after the release of its second successor, the Game Boy Advance, in 2001.