It's a bit hard to believe now, but back in the early '80s RPGs were a fairly unknown genre in Japan; Dungeons and Dragons hadn't been brought over and only a handful of people were aware of computer games like Ultima and Wizardry that were making a splash overseas. Seeing opportunity, one Henk Rogers (who would later have a very prominent role in introducing Tetris to the wider world) would develop and release a D&D-inspired RPG and release it on the PC-8801. That game was The Black Onyx and it was a huge hit, selling about 150,000 units (with many more likely playing it through pirated copies) and getting numerous ports and expansions in subsequent years. It was a pretty full-featured game for the time, too - you could choose a wide assortment of heads and bodies to make custom avatars, and equipped gear would even show up on their sprites. It had full-3D mazes, enemy groups with their own visible avatars, and even the ability to try and talk your way out of battles. While there is no magic system or ranged weapons, there were shops to upgrade equipment, pubs and stores to interact with NPCs, and even a bank to store money so it wouldn't get stolen by robbers. So if you're a fan of Final Fantasy or Dragon Quest or basically any other game that can trace its lineage back to D&D, well, here's a link in that chain you may not have even known about until now.
Developer: Bullet-Proof Software
Publisher: Bullet-Proof Software
Released: 1984, 1985, 1987, 1988, 2001
Platforms: PC-8801, MSX, FM-7, SG-1000, Famicom, Game Boy Color