Nintendo Life: The Super Nintendo (even in Japan) was marketed as a family friendly system, something easily proven by taking a glance at its excellent game library. Despite that, you can find yourself a few horror gems targeted at a more mature audience that naturally never made it out of Japan. KSS produced one such game: Majyuuou (literally "King of Demons"). You might dismiss it as yet another Castlevania wannabe, but dig a little deeper and you will quickly realize that Majyuuou makes the Belmont saga seem like a kid friendly matinee.
One modder produced an unofficial, modern-day take on the Game Gear.
Video Gamer writes: "There's a rogue underworld of devs operating clandestinely, still creating Game Boy games. We've spoken to one of them."