There have been many developments in computer chess over the past 20 years, ranging from one of the earliest available, the Rasputin, up to Deep Blue, a number-crunching mainframe which drew with Gary Kasparov ("There must be a bug in the software, otherwise it would have beaten him", remarked the programmer). One of the latest is Power Chess, from Sierra Software.

Amongst serious chess players, practising against a computer is not as popular as one might think. All the top players these days have ChessBase or some other database program upon which to store their own games, or, more importantly, to research the games of their next opponents. CD Roms containing hundreds of thousands of games are available (at a price) and of course the games from important international tournaments are available on the Internet within a few hours of the games having been played.

But ChessBase itself is not an opponent: it is merely a storage device, albeit a very sophisticated one. The program which actually plays the game, and is compatible with ChessBase, is Fritz. Fritz version 4 was one of the first programs, loaded onto a Pentium computer, which actually managed to beat Gary Kasparov at a rapidplay game. Fritz has been around a long time, and is a reliable product. However, it is still a computer, and according to one source, chess players get bored with computer opponents because "computers don't squirm".

Power Chess is a very sophisticated program which is designed to "humanise" the computer. The "engine" driving the software is the Wchess program, which succeeded in drawing a game with Deep Blue, an impressive result for a PC when playing against a mainframe. However, one of the biggest criticisms levelled at the vast bulk of chess-playing software is that the only way to make it play more weakly is to make it play more quickly. This is the fundamental drawback when using computers as a coaching tool: chess coaches are forever telling their students to slow down, yet for a moderate player to stand any chance against a modern computer (by which I mean anything running faster than 66MHz) it has to be programmed to give instant reponses to the student's moves.

Power Chess has solved that problem in a very interesting way. Firstly, the student can select the opponent. There are many different characters from the Royal household, each of whom knows how to play chess. The Queen is the strongest player, and to play against the Queen is to select a very powerful opponent indeed. The King, however, is the opponent whose characteristics make Power Chess different from every other chess program I have seen. The first time you play against him, the software sets up a personal record for you which records the games and re-calculates your rating each time you play.

Initially the King plays very weakly. He begins by allowing Fool's mate ( 1 e4 f6 2 d4 g5 3 Qh5 mate) and in game two he blunders his queen. Having now lulled his opponent into a false sense of security, he begins to play much better, and game three is a real contest. What is happening here is that the software is continually re-assessing your playing strength and selecting moves which it considers would be chosen by a player slightly stronger than yourself.

This leads to an excellent contest. In my third game against the machine, I had reached a position which was probably drawn (R v R & P) in which the computer had the pawn. It was at this point that I fell foul of another aspect of the software which sets it apart from other chess-playing programs: in king mode, it will not let you take moves back! I am a clumsy computer user, and when moving my rook, I released the mouse button at the wrong moment and the rook landed on g6 instead of h6. This cost me a move and the computer's pawn queened!

This is a good lesson in discipline. One of the most used features of chess software is the take-back facility, and of course this is not allowed in human chess. Playing against the Power Chess King forces you to play only the move you have seriously considered as being the best, and it also forces you to devote time to the game. Once a game is started, the only ways to stop it are to resign or win.

Once your game is over, the post-mortem begins. The Queen will speak to you (she is the best player in the Royal household, having spent many hours studying while her war-like husband is off burning villages) explaining mistakes and praising good moves in a reasonably attractive American accent. She is on your side, meeting some of the King's errors with such expressions as "Gee, what a goof-up!", whereas your own mistakes earn the gentle chiding "I don't think that was best."

Another attractive feature of Power Chess is the use of Fischer timings, so that each player has a set amount of time plus more time per move. That means that, provided you keep the moves ticking over at a reasonable rate, you need not get into time trouble.

Power Chess is the best computer opponent I have yet come across.

The system specifications required to run Power Chess are Pentium 60 PC with Windows 95, some spare hard disc space and at least Double Speed CD Rom.

Khalifman,A - Vulfson,V St.Petersburg 1995

1.d4 d5 2.c4 dxc4 3.e4 c5 4.d5 e6 5.Nc3 exd5 6.Nxd5 Nf6 7.Bxc4 Nxd5 8.Bxd5 Be7 9.Ne2!? 0-0 10.0-0 Nd7 11.Nc3 Nb6 12.Bf4 Bf6 13.e5!? Be7 14.Be4! Qxd1 15.Rfxd1± g5 16.Be3 Rb8 17.b3 Be6 18.Nb5 Nd7 19.f4! gxf4 20.Bxf4 c4 21.bxc4 Nb6 22.Nd6 Nxc4 23.Nxb7 f6?! 24.exf6 Bxf6 25.Bxb8 Bxa1 26.Bxa7 Bc3 27.Nd8!+- Bg4 28.Bd5+ Kh8 29.Nf7+ Kg7 30.Rc1 Ne5 31.Rxc3 Nxf7 32.Rg3 1-0