Bio-Defence, from Tymac, appears to be an original idea in computer software. The object of the game is to keep a patient's temperature below the level at which he dies.

There are two separate parts to the game. In the first, an outline of the human body is displayed horizontally across a grid of approximately 500 squares.

Using a joystick, you move a cursor from square to square within the body outline until you find an area of infection. There is no skill attached to finding this - it just suddenly appears, indicated by an orange dot.

From here you progress on to part two. This scenario is acted out in the infected area, which is laid out like a maze.

You play the part of what appears to be a white cell, looking something like an amoeba, and your task is to soak up most of the bacteria around you. I say "appears" because there were no instructions with my advance review copy and surprisingly, none on the screen.

There are, in fact, several different sizes of bacteria and you should only be chasing the smaller ones. Any contact with the largest variety results in a darkening of your colour.

Should you contact these too often within a short space of time, you turn black and die and the patient's temperature rises by one degree.

You can eat the big blobs but you've got to time it right, hiding in your niche at the bottom of the screen. Of course, while you're hiding the bugs are multiplying.

Should you succeed in absorbing all the bugs, you automatically return to the first part of the game and start to search again for another infected area.

Once you find one it's back to work as a bug gobbler until such time as you get zapped too often by the big boys, and the patient's temperature gets so high that he snuffs it.

The more successfuly you are in your bacteria bashing the more numerous and vicious are the enemy in subsequent locations.

The graphics are quite nice but don't really do the Atari justice, and the sound is nothing to write home about. An attempt has been made to synthesise speech, but the result is almost unrecognisable.

The game was fun the first few times I played it, but I didn't find enough variety to maintain interest.