Revs first appeared a couple of years back on the BBC, and was converted to the Commodore 64 in february of last year. It was met with almost universal acclaim, although some users complained about the lack of a digital joystick option - the program only allowed control via an analogue joystick, paddle controller or keyboard.

Now, a year an a half later, Geoff Crammond has taken his original program and enhanced it, adding an extra four tracks, a digital joystick option and 'computer aided steering'.

For the unitiated, Revs Plus is a simulator of the Ralt 3 Toyota Novamotor. 'Simulator' is the operative word - there's no 'climbing into the cockpit' and zooming off at silly speeds like most race game. The author has tried to get the program to react as much like a real car as possible, and although the computer car has no clutch and is tolerant to excessive over-revving, it requires plenty of practice before you can even corner properly.

The 'car' comes equipped with six gears (five forward and one reverse), brake, throttle, and adjustable aerilons.

The action is viewed from the driver's seat, with the cockpit controls at the screen bottom. The rev counter takes a central position, and is used in place of a speedometer - showing the power of the engine, rather than the car's velocity. Wing mirrors at the bottom left and right show approaching opponents during the race section.

Simulated practice and racing takes place over six famous tracks, Brands Hatch, Donnington Park, Nurburgring, Oulton Park, Silverstone, Snetterton - with only two loaded at any one time. The corners, hills and bumps of each circuit have been faithfully squeezed into the 64.

At the start there are two options: practice on an empty track, or race competition. The latter requires the negotiation of a series of qualifying laps in preparation for a race. The field contains 20 cars, with the speed of your qualifying lap affecting your grid positions.

Should you car skid off the track or collide with another contestant, it returns to the track at the point of collision and has to be started up again. If another car is in the accident it is left on the track, and causes an obstruction throughout the rest of the race.

The graphics, although plain, give a real 3D effect, with the hills and bumps of each course uncannily 'felt' as you drive around. Even though the car is difficult to handle and takes an awful lot of practice to master, the program remains addictive - for me, a lot of the joy came when I completed my first lap without crashing. Buy this outstanding program if you've got any interest in motor racing.

However, I found that the initial difficulty encountered in controlling the vehicle was more than a little offputting. It is hard to pigeonhole Revs Plus: it is more than a racing game, but less than a true simulation. I enjoyed my a few clear runs around the race-tracks of the world, but the novelty eventually wore off.

Another problem is the sound which is well below the standard set by the rest of the program - an almost apologetic little buzz takes the place of the engine's roar. Revs Plus is a genuinely absorbing and exciting product, but the level of practice necessary to even complete a singla lap was too high for my liking.