So few titles were made and released for the Sega Game Gear that it's hard to believe any of them could be considered overlooked.
The fact remains, though, that the masses basically ignored this brick-sized "portable" system, so it's probably safe to say they did the same to its meager (compared to its main competitor, Nintendo's GameBoy) games library while the bulky handheld was on the market from the early to mid 1990s.
And not only that, but the masses continue to ignore the system and its catalog. Think your average game fan turns his or her nose up at the GameBoy (and, believe me, they do) these days? At least they've likely heard of Nintendo's first handheld. The same can't be said of the Game Gear or the overlooked "gems" discussed here.
Alien Syndrome--I have a feeling a lot of people pass on this version of Sega's Alien-inspired run-and-gun shooter because they assume it's a turd. In reality, it's better than both the NES and Master System ports of the 1987 arcade game. Sadly, the Game Gear iteration of Alien Syndrome offers platers just four stages, but they're challenging--and fun--enough that most who give it a shot won't care. (Bonus: the Japanese release sports a superb piece of cover art.)
Berlin no Kabe (aka The Berlin Wall)--If you're a fan of single-screen platformers, you'll adore this portable reimagining of Kaneko's oddly named quartermuncher from 1991. Not only is Berlin no Kabe cute as can be, but its gameplay is a breath of fresh air. I mean, what's not to like about creating traps for a colorful cast of baddies by using a hammer to smash holes in the floor beneath their scampering feet?
Bubble Bobble--Here's another Game Gear title many folks likely ignore because they imagine it's not worth their while. Or maybe they think it's just a port of the Master System version of Taito's classic arcade game. Whatever the reason, those who own a Game Gear but have yet to pick up a copy of Bubble Bobble are doing themselves a disservice. This remake (of sorts) features miniaturized stages and full-sized Bub, Bob and enemy sprites, which results in a strangely unique--as well as strangely enjoyable--experience.
Ganbare Gorby! (aka Factory Panic)--Honestly, I'd consider this Sega-made oddity worth buying and playing even if it weren't much fun thanks to the fact that its protagonist resembles former president of the Soviet Union Mikhail Gorbachev. Thankfully, it is fun. Although its box cover suggests its a puzzler, a more accurate way to describe it would be to call it an arcade-style action game. (Not enough info for you? You press switches to change the course of a series of conveyor belts, with the goal being to deliver products like bread and meat and medicine to needy citizens.) Ganbare Gorby! isn't groundbreaking, to be sure, but it's also not a bad way to waste a bit of free time.
Magical Puzzle Popils--Made by Fukio Mitsuji, the man who's chiefly responsible for giving the world both Bubble Bobble and Rainbow Islands, Magical Puzzle Popils (Popils: The Blockbusting Challenge in Europe) is the best Game Gear cart around in the opinion of yours truly. Unlike the aforementioned titles, Popils is a brain-busting puzzle game with eye-pleasing graphics and an ear-pleasing soundtrack.
See also: five overlooked GameBoy, Famicom, PC Engine and PlayStation games you need to play as soon as possible