Reversi is a late nineteenth century board game. Mine Of Information's computer version also goes under the name "Othello". It is a game of skill between two players using a draught board. Counters, black on one side and white on the other, are used. A move is made by placing a counter on a vacant square next to an opponent's counter, and each move must result in the 'capture' of an opponent's piece - a capture is made by trapping a counter showing the opponent's colour (or a line of such counters) between the new counter and one showing your own colour already on the board. The game ends when neither player can make a capture. The winner is the player with the largest number of counters showing their colour.

Now to MOI's game. After loading the cassette, a menu is displayed and you can choose to play a game against an opponent, a game against the computer, a 'sample' game, or to change the start position. Using this latter facility you can select for yourself a few advantageous positions - the corners for example - to give yourself a chance against the computer! For the novice, the sample game is very useful for gaining familiarity with the rules and learning something of the strategy behind the game. You can go forwards and backwards through the sample game so that the effect of each move can be clearly seen.

The board is displayed on the screen with the square co-ordinates (A to H on the horizontal axis, 1 to 8 on the vertical scale), displayed along the board edges. White and black pieces are denoted by 'O' and 'inverse O' respectively. The display includes the current score and the co-ordinates of the last move. After each move, the computer 'flashes' the pieces captured for a few seconds - a nice touch.

The computer checks that the chosen moves are valid. Each time it is your turn to move, you can call up various game options - change level of play, replay last mvoe, change sides, pass or return to Basic. There are nice levels of play, the response at levels 1 and 2 is practically instantaneous; levels 4, 5 and 6 take about three, 10 and 40 seconds respectively, up to level 9 which takes a very long time indeed. Harder levels of play take longer as the computer looks further ahead and so has more possibilities to evaluate. I was somewhat disconcerted when I first tried level 9, the screen goes blank and after waiting for a while, nothing happened and I thought the program had crashed. It would be nice if the board was displayed, perhaps with some reassuring message such as 'wait please, I am thinking', whilst the computer evaluates its next move. At least you can then ponder your following move.

The hardest levels really take far too long between moves for a sensible game to be played. In any case, levels 1, 2 and 3 are hard enough for even a good player. If you can beat it at level 4 you must have played this game before, to beat it at level 5 you must be very good indeed!

The cassette is recorded on both sides, and the game takes about three minutes to load. It is written almost entirely in machine code. Well-written instructions, complete with some hints on tactics and strategy, are included in the package. Reversi is a very sophisticated program, easy to use and enjoyable to play. It is probably the best 'Othello' program for the ZX81 on the market, and will certainly improve the play of both beginners and more experienced players alike.