Reversi

The single biggest mistake in Reversi is chasing the move that flips the most discs, especially in the first half of the game. It feels productive, but a board covered in your colour early on is often a weak position, because it also hands your opponent more of your discs to recapture later and pushes you toward the edges and corners in ways you did not choose. The corners are the important squares, because a disc sitting in a corner can never be flipped back by either player, no matter what happens afterward. The four squares diagonally, vertically and horizontally next to an empty corner are the ones to be wary of, since playing on one of them very often hands your opponent the corner itself on their next turn. Our Medium and Hard computer opponents both play with this in mind, favouring corners and steering clear of the squares beside an open one, so playing against them is a good way to feel why the advice holds.

A second thing worth knowing: the game can swing hard in the final few moves. A board that looks comfortably yours with ten squares left can flip most of the way over on a single well-placed disc near a corner, because so many discs can be caught in a long line at once. It is worth counting corners and edges, not just today's disc total, when you are judging how the game is going.

The board is large and each disc is shown two ways at once, not just by colour: the dark disc has a light ring around a near-black fill, and the light disc has a much heavier dark ring around a near-white fill, so the two are easy to tell apart even at a glance or in poor light. Legal moves are always marked, so no square goes untried simply because it was easy to miss. The corners themselves carry a quiet marker of their own, since they matter more than any other square on the board.

There is no timer anywhere in the game, and nothing about a finished game is kept once you start a new one; the running disc count you see while playing is only there to help you read the board as it stands. Undo takes back your last move together with the computer's reply to it, so a slip never has to end the game, and Hint will always tell you why it suggests a square rather than simply playing it for you. Three difficulties are on offer: Easy takes whatever flips the most discs, Medium plays for corners and edges the way a careful newcomer would, and Hard adds a short look-ahead so it weighs your likely reply before committing to a move.

If you enjoy games of this kind, you may also enjoy our Checkers and our Four in a Row, or browse all of our board games and the full collection of free games.

How do I play Reversi?

You play the dark discs and always move first. Every square you may legally play on shows a faint marker, so there is never any hunting for a move. Tap a marked square and your disc lands there; any of the computer's light discs caught in a straight line between your new disc and another dark disc flip over to become yours. The computer replies after a short pause.

What counts as a legal move?

A move must trap at least one of the opponent's discs in a straight line, horizontally, vertically or diagonally, with one of your own discs at the far end and nothing but opponent discs in between. If you have no such move anywhere on the board, you simply pass and the computer plays again.

What do the three difficulties change?

Easy always takes whichever move flips the most discs right now, so it can be out-thought. Medium favours the corners, avoids the squares that hand a corner away, and only then looks at flips. Hard adds a short look-ahead, weighing your best reply before it settles on a move, so it plans a little further than the move in front of it.

What does Hint actually tell me?

Hint never just plays the move for you. It names the reason: that a square takes a corner and a corner can never be recaptured, that a square sits on the edge where discs are harder to surround, or simply that it flips the most discs on offer right now. Press it as often as you like.

Is there a timer or a score kept between games?

No. There is no clock and nothing is remembered once you start a new game. The running disc count during a game is just there so you can see how the board stands; nothing about it is saved or compared game to game.

Reversi was introduced in England in the 1880s, and almost from the start there was a dispute about who invented it. Two men, Lewis Waterman and John Mollett, each claimed credit and accused the other of copying his idea, and the argument was never conclusively settled. What is not in dispute is that the game, flipping an opponent's discs by trapping them between your own along a line, spread quickly once it was on sale.

The game faded, then returned from Japan in the 1970s under the name Othello, a trademarked version with standardized rules that made it popular worldwide and is often what people picture first when they think of a game like this. Our version keeps the older name and the same underlying idea: flip the discs, hold the corners, finish with more of your color on the board. Compare it with our other board games.