This was mind blowing when it came out, smooth procedural "fractal" landscapes. In the days when the triangles were substantial...
I had the pleasure of playing it at school as we had a single acorn archimedes and this got thrashed by us. I think ti was just a demo at the time...
Later on in got released for the Atari and Amiga and I got to play it properly - i think it was renamed to Virus, the game was known for it's unforgiving nature and physics.. yet responsive, you had to put in some time to understand how to fly the ship let alone kill the aliens...
Nowadays that kind of difficulty is usually at the far end of a sliding scale, from "Disneyland" to "Evil".
From a time when simplicity and elegance were generally part of the game development landscape...in my opinion we have lost a lot of that ethos between here and there...
Top game, one of the cornerstones.