The idea of defending a body from the invasion of a talking virus is certainly novel and should have resulted in a beuer game than this.
At the start, the virus introduces itself as "I nectorf M" and informs you that it is active. The main screen shows a human outline drawn over a mapping grid along with the body's present temperature and a nice EKG display which blips away cheerfully while the body is healthy.
Your joystick controls a target square moving across the grid. When it is over a highly infected area a star lights up. A quick press on the trigger then takes you into the patient's bloodstream where you become a white corpuscle chasing after lots of black dots and chains in a simple maze. You destroy the virus by swallowing all the dots. Eating too many of the chains too quickly causes the corpuscle to turn black and die and raises the patient's temperature; when it reaches 108 degrees the patient dies.
The movement of the corpuscle is well done, but the other graphics used in the game are poor and make no use of the Atari's capabilities.
The virus speaks with a deep, gutteral voice which is very hard to understand. In fact the only thing that kept me playing this game was the need to hear the spoken phrases several times to understand them.
A set of instructions might have helped, but at £9.95 this game will always be poor value for money.