This game was written by David Braben in a matter of weeks (allegedly) to show off Acorn's next generation machine, the Archimedes, in the late '80s (when it was called Zarch) but it wasn't until the game was converted to the more popular Commodore Amiga that it found favour among the more adept gamesplayers of the day.

Essentially a 3D shoot 'em up, the player had control of a small spaceship from which they had to defend a series of landscapes from alien invaders who spread a virus over the land, killing all the flora. The player merely tried to despatch as many of the alien invaders as possible before running out of lives. And to start with, you were your own worst enemy. The control method employed took some serious getting used to. Novices would, invariably, spend the first half hour ploughing their ship into the landscape - much to the casual gamer's frustration.

Perseverance paid rewards though because once the control method was mastered it became a dream to use, consummate players could swing their ships all over the landscape with gay abandon and go chasing after the - gasp - intelligent alien enemies, some of whom were so devious, the sound of their approach would cause beads of sweat to appear on their brow.

Virus was critically acclaimed and managed to sell in reasonable numbers but it wasn't until last year that Grolier Interactive published the game's first proper sequel - V2000 on the PC. Although Virus was innovative it was rarely cloned, the only team brave enough to attempt it being Binary Asylum with their fabulous 3D helicopter shoot 'em up, Zeewolf. David did allow his landscape engine to be used in the also rather splendid tank battle game Conqueror.