The Black Onyx is among the first western-style RPGs to be developed in Japan, produced by BPS, with development led by Henk Rogers. It was ported to multiple systems, mostly the usual suspects like X1, PC-8801, FM-7, and MSX, but also Famicom, Sega SG-1000 (on a My Card), and this one - the PC-8001mkIISR.

Very few games actually demanded an SR, usually games are developed for the vanilla PC-8001 or more advanced and widely available PC-8001mkII. The only use of the FM sound that I've noticed so far is the title screen song. It will not load on a PC-8001mkII, so maybe it is leveraging some other technology available to the SR model in particular. It seems to use a full eight color palette during ganeplay.

In most of the implementations I've run across, the game is on cassette tape and uses both sides. There is a "Rollem" side that you use to generate your characters. You do get to customize your characters' appearances, but the overall design is pretty simple.

After that, you load the "Onyx Game" side and begin your adventure. Upon loading, you are met with the title screen, where you can elect to play the title screen music or jump straight into the game. Once you choose the music, you seem to be locked into it until the music finishes.

Once you choose to start the game, you are placed into the top level of the maze and you can run into some enemies as well as other dwellers who may or may not be open to joining your party. There are also a variety of establishments where you can prepare for your dungeon-crawling adventure.

You can find entrances to the various dungeons around the ground level, and the enemies waiting beneath have ramped-up difficulty, so be ready! There's no visual entrance to the dungeons, you have to pay attention to the captions as you traverse the grid.

The game box and manuals were in quite good condition after these 40-odd years.