In 1996 Sega dropped support for anything that wasn't the Saturn. The Game Gear was a victim of this process. Despite being technically superior, it never kept pace with the Game Boy. Sega finally threw in the towel in 1996 but still snuck out one last game, Sonic Blast. Don't let the name fool you though, this is not a port of the Sega Genesis game. It's your typical 2D, side-scrolling Sonic game.
The Game Gear would be briefly re-released in 2000 but no new games were published.