Work began on the console after the Game Boy's release in 1989. At that point, the project was codenamed Project Mercury and they wanted to make a product better than Nintendo's Game Boy.
The Game Gear was basically a pocket Sega Master System, though it seemed to have arguably better graphics due to the larger color palette. It was superior to the Game Boy, due to the color screen and TV Tuner. The system is held lengthwise at the sides, preventing the cramping of hands that plagued the Game Boy.
However, despite its technical superiority, it did not gain a significant market share due to the enormous popularity of the Game Boy. It did have a few setbacks: the backlit screen meant that the batteries onbly lasted three to five hours, and the Game Gear was a rather large and bulky system. The market at the time wanted lightweight and more battery life. The Game Boy excelled over the Game Gear and other competitors because of this. Mostly, however, the Game Gear suffered from a lack of quality games, as Sega failed to sign up as many key software developers as Nintendo.
Because of the similarities between the Master System and the Game Gear, Master System games had been burned on ROMs on Game Gear cartridges. Likewise, a Master System to Game Gear Covertor, the Master Gear, had been released, which allowed Master System games to be played on the Game Gear. The reverse could not be done, as the Game Gear had a higher color palette.
Today, the Game Gear is widely considered to have been a failure, and unlike the Game Boy no newer versions were released. The Game Gear, however, did better than other portable systems that tried to compete with the Game Boy. Support ended in 1997, but Majesco released a Core version of the Game Gear in 2000 for a reduced price.