Silpheed is a well done shoot-em up game, something that can be a bit difficult to pull off on Japanese 8-bit computers because most of them lacked the ability to do vertical scrolling in hardware. Most games in this genre that I've encountered on Japanese 8-bit platforms are very simple, never-ending waves of several designs of basic enemy ships, atop a black background, maybe with stars. Not that it's bad, but simple.

Silpheed uses the black background technique for much of the game, and I think a monochrome background is probably key to making a vertical shoot-em up playable on the system. That said, there is at least one scene with a more complex background, at the apparent expense of some speed.

But the real win is that the developers spent some time on the details. There is an intro with FM soundtrack. You get weapon upgrades. You have boss battles with substantially larger sprites. There's a unique 3D perspective and if you are good enough (I am not!), can actually achieve a goal that they set out for you. This makes for a much more engaging gaming experience.

Update: sometime later I came across a boxed version. The box was incredibly dirty and warped, the manual was missing, and the floppies were scratched and didn't boot. Most of the dirt came off the box, at least.