The Game Gear is an 8-bit fourth generation handheld game console released by Sega on October 6, 1990 in Japan, in April 1991 throughout North America and Europe, and during 1992 in Australia. The Game Gear primarily competed with Nintendo’s Game Boy, the Atari Lynx, and NEC’s TurboExpress. It shares much of its hardware with the Master System, and can play Master System games by the use of an adaptor. Sega positioned the Game Gear, which had a full-colour back-lit screen with a landscape format, as a technologically superior handheld to the Game Boy.
You can browse and download most available games for free below, but you will need an emulator also to play them. For Sega Game Gear we recommend https://www.carpeludum.com/kega-fusion/ but you can use any emulator of your choice and even original hardware if you have the know how!