With a full-color backlit screen, a landscape format and a more powerful Z80 CPU, Sega positioned the handheld device as technologically superior to the Game Boy.

Developed as codename "Project Mercury",[5] the Game Gear was launched in Japan on October 6, 1990,[6] in North America and Europe in 1991, and in Australia in 1992.

The console had been designed as a portable version of the Master System, with more powerful features than the Game Boy, including a full-color screen instead of monochromatic.

Sega's marketing in Japan did not take this perspective, instead opting for advertisements with Japanese women featuring the handheld, but Sega's worldwide advertising prominently positioned the Game Gear as the "cooler" console than the Game Boy.

One Sega advertisement in early 1994 features the quote, "If you were color blind and had an IQ of less than 12, then you wouldn't mind which portable you had.

"[10] Such advertising drew outrage from Nintendo, who sought to have protests organized against Sega for insulting disabled persons.

Sega of America president Tom Kalinske responded that Nintendo "should spend more time improving their products and marketing rather than working on behind-the-scenes coercive activities".

[5] Marketing in the United Kingdom includes the slogan, "To be this good takes Sega", and advertisements with a biker.

[10] In the United Kingdom, the Game Gear had a 16% share of the handheld market in January 1992, increasing to 40% by December 1992.

[16] Though the Nomad had been released in 1995, Sega did not officially end support for the Game Gear until 1996 in Japan, and 1997 worldwide.

The chip generated stereo sound, audible using headphones as the device only included a single monaural speaker.

[5][6] The screen is backlit for low light using a small cold cathode fluorescent lamp tube.

[10] To lengthen play time and reduce consumer cost, Sega released two types of external rechargeable battery packs.

[7][23] Available accessories included a TV Tuner with a whip antenna for the cartridge slot, to become a handheld television.

[29][30] A special version of the device (published by M2 and licensed by Sega) was being shipped with a limited edition of Aleste Collection in December 2020.

In 2008, GamePro listed the Game Gear as 10th on its list of the "10 Worst-Selling Handhelds of All Time" and criticized aspects of the implementation of its technology, but also stated that the Game Gear could be considered a commercial success at nearly 11 million units sold.

"[32] In speaking with Famitsu DC for its November 1998 issue, Sato stated that the Game Gear achieved ''a respectable chunk of market share'' since overall ''about 14 million systems'' were sold, but that "Nintendo's Game Boy was such a runaway success, and had gobbled up so much of the market, that our success was still seen as a failure, which I think is a shame.

How many batteries did we suck dry playing Sonic, Madden and Road Rash on the bus or in the car, or in the dark when we were supposed to be sleeping?

Content and innovation beat out technology, a formula that Nintendo is using right now with the continued ascendance of the DS and Wii."

Buchanan praised some of the library: "Some of those Master System tweaks were very good games, and fun is resilient against time.

"[8] Retro Gamer praised Sega's accomplishment in surviving against the competition of Nintendo in the handheld console market with the Game Gear, noting that "for all the handhelds that have gone up against the might of Nintendo and ultimately lost out, Sega's Game Gear managed to last the longest, only outdone in sales by the Sony PSP.