ONCE upon a time, before the fateful day when Clive Sinclair got his first tricycle, computers were rare. Huge mental cabinets filled with valves and filling large areas of university labs, they were designed and used by mathematicians.

It was confidently predicted that there would only ever be six computers in Britain because it would be impossible to train enough mathematicians to operate more. The mathematicians got quite excited by this, sensing a chance for a real job at last.

But sanity prevailed. Nowadays, any intrusion of mathematics into computing is viewed, quite rightly, with suspicion. On odd occasions a pure mathematician does chance across a computer; a progeny of just such a strange match is Whirligig.

Take the game screen. In the middle sits a comfortably familiar, if a little angular, 3D shaded spacecraft. Shame about the colours, but you can't have everything. But the area around the craft isn't yer ordinary hard interplanetary vacuum in which a thousand heroes have died, my goodness no. It's eigen

Eigen is number

An eigen

You'll find a fuel store in an eigen

All this wonderful number

The only fun about is shooting at the ships which guard the solids. As some of these are invincible, you might have to run away.

This game is for retired professors who find spreadsheets just a little too exciting for the old ticker. Mediocre graphics - sprites dressed up as 3D solids with a light source - poor mouse control and frustrating screen changes, combined with hyperactive marching music, might put the rest of us off. Spend your twenty quid on Russell & Whitehead's Principia, it's much livelier.