This game is also known as Sagaia
The arcade game Darius used a unique system that attached three monitors together to create one massive horizontal playing field (also used in Taito's Ninja Warriors.) Naturally, this couldn't quite be replicated on the console system, so that nifty little gimmick is lost, but emulators can still replicate the dimensions of the screen, even if you end up looking at a tiny picture.
For some strange reason, Darius 2 was changed to Sagaia outside of Japan. Most people are probably familiar with the Genesis port, which was quite good. The graphics obviously suffer a little bit, as does the music (and no more goofy take-off sound bite), but otherwise it makes the transition quite nicely.
Sagaia also made it to the Sega Master System in Europe - and also pulls off a magnificent port that looks amazing for an 8-bit system. The only real knock against it is that several levels had to be cut to fit in such a small cartridge.