Gyron is modestly described by its producers Firebird as the most challenging computer game ever written. Judging by the prize on offer, they may not be far wrong. However, more of that anon.

You control a Cyron, a remote-controlled probe robot with the task of penetrating the defences of an enemy computer and then destroying it. The defence system consists of a giant maze which is in turn protected by a series of towers and balls. The balls are giant robots which are immune to your weapon systems. They move round the maze in a present cyclical pattern. The balls effectively act as moving sections of maze wall.

The towers are merely intent on destroying you in their field of destructive energy. They can be deactivated by sneaking up behind them and using your laser on them.

Control of the Gyron is effected either through the cursor keys or joystick (Kempston interface0. The screen is divided into fire windows. The main screen shows the view from your Gyron. The 3D walls redraw themselves very quickly and smoothly as you move round the maze. The balls and towers are very cleverly masked behind these walls, giving a very menacing and sinister feel to the whole thing. Full marks for atmosphere created. Indicators on the main screen give details of your lateral position in a passage (vital this for avoiding towers) and also of approaching side passages.

The other four windows are from top to bottom a radar scanner very difficult to use. Every time you turn a corner, the picture reorientates itself so that it gives the same view as the main screen. This makes mapping very difficult and had the effect of making me go round in circles; perhaps I just don't have a natural sense of direction.

An interesting feature of the zone indicator is that it displays the spinning icosahedron in one of twelve different colours. Very clever considering that there are only eight colours in a normal Spectrum display!

The prize on offer for completing your mission is a Porsche no less. As is well known, this is the car driving by games programmers (but not alas games reviewers!). Before you consign your old jalopy to the scrap heap though, here are a few points to ponder. You will not be able to hack your way into the code and come up with a password or similar. You will be invited to a grand final where you will have to demonstrate your prowess.

The tapes comes with two versions of the game on it. An easy version called The Atrium and the competition version. At least that's how Firebird describe it. This is obviously a new meaning of the word "easy" I have never come across before! I think that it will be some time yet before I drive away in that Porsche!