How to win at Reversi

The board is 8 by 8, 64 squares. It starts with four discs in the middle, two each, set diagonally. You place a disc so that it traps a straight line of your opponent's discs between it and another of yours, across, up and down or diagonally, and every trapped disc flips to your colour. One move can flip lines in several directions at once.

If you can't make a move that flips something, you pass and your opponent goes again. The game ends when neither of you can move, which can happen before the board is full. Whoever has more discs wins, and an equal count is a draw.

A disc in a corner can never be flipped. To flip a disc it has to be trapped between two of the other player's, and a corner has nothing beyond it on any line. Once you have a corner, it's yours for the rest of the game, and so is any straight run of your discs growing out from it along the edges.

Edges are the next best thing. A disc on an edge can only be flipped along that edge, because every other line through it runs off the board on one side. That makes edge discs hard to take back, as long as you're careful about what they let your opponent do along the edge.

The square diagonally in from each corner is the worst square on the board early on. Take it while the corner is empty and you've usually given your opponent a line into the corner. The two squares beside each corner on the edges are risky for the same reason, a little less so.

Our computer plays with a table that says the same thing in numbers: a corner is worth 100, the square diagonally in from it is worth minus 50, and the two squares beside it on the edge are worth minus 20 each. Most of the middle squares are worth 1.

• Stay off the squares next to an empty corner unless you have to.
• If your opponent takes one, check whether you can now reach the corner.
• Once a corner is taken, the squares beside it are safe to use.

In the middle of the game, having lots of discs mostly means having lots of discs that can be flipped. What matters more is how many moves each of you has. A player with few moves gets pushed into the squares they didn't want, like the ones next to an empty corner.

So prefer the quiet move that flips one or two discs and leaves your opponent with few choices over the big move that flips eight and opens up the board. Hard on ScampLabs plays this way: it counts the moves each side has left and weighs each one as 8 points, on top of the squares, and adds 25 for each corner it holds more than you.

Near the end, discs finally count. The last few moves flip whole rows, so keep counting right to the final disc rather than trusting how the board looks.

Passes matter here too. If you can play so that your opponent has no move, you get two in a row, and that late in the game two moves in a row can swing a lot of discs.

They're the same game today. Reversi is the older name, from 19th-century England, where the players chose how the first four discs went into the middle four squares. Othello is the version sold since the 1970s, with those four discs always set diagonally and dark always moving first. Our board uses the Othello start.

Easy plays any legal move at random. Medium looks at the squares only: it takes the move that leaves the best-scoring board by the table above, without looking at what you'll do next. Hard looks 4 moves ahead, yours and its own, and counts squares, moves and corners.

Medium almost never turns down a corner, which makes it a good teacher for the squares you should leave alone.

It’s free in your browser, with no sign-up. Play Reversi against the computer, with a friend on the same screen, or send a friend a link and play online. Or tap Quick match to play someone new.

More guides