Virus is a 3D ‘shoot ’em up’ which requires the player to control a small wedge-shaped fighter as it flies over an undulating patchwork landscape of fields, trees and the occasional building. The player’s nemesis is an enemy ship which is spreading a virus across the land, hence the title of the game.
There are a number of different enemy ships to destroy, and this requires pin-point accuracy with your ship's bullets and rockets within the 3D environment.
Although you can play the game with keys, most hardened game-players use mouse control on the 16-bit versions.
The ship has a limited number of rockets to begin with, and fuel will only last so long before you have to head home to the landing pad so you can automatically refuel.
Once the ship is tanked up again, it's time to take off and destroy the required number of ships before progressing to the next level.