Virus

Virus is the Spectrum version of David Braben's Zarch, a 3D shoot 'em up in which you fly a lander over a landscape drawn in solid perspective. Alien seeders spray a red virus across the land, and you have to shoot them down before the infection spreads. Your craft is steered by rotating and thrusting, which takes a lot of practice, but it can fly in any direction over the scrolling terrain.