How to play Reversi

Reversi is a two-player board game of black and white discs on a green board of 8 by 8 squares. Every disc is black on one side and white on the other, and discs change hands all game long. It takes a minute to learn and a long time to master. At the end, the player with more discs showing their color wins.

The start

Four discs begin in the middle of the board, two of each color, set diagonally. Black moves first, then the players take turns. You play Black against the computer unless you choose White in Settings.

A move: trap and flip

• Place one disc of your color on an empty square so that one or more of your opponent's discs sit in a straight line between your new disc and another disc of yours.
• The line can run across, up and down, or diagonally, and it cannot have gaps. Every trapped disc in that line flips to your color.
• If your new disc traps lines in several directions at once, all of them flip.
• A move must flip at least one disc. The dots on the board show every square where you can play. On a computer, point at a square to see which discs it would flip. On a phone, the first tap shows it and the second tap plays.

Passing and the end

If you have no square that flips anything, you pass and your opponent moves again. You cannot pass when you have a move. The game ends when neither player can move, usually because the board is full. Count the discs: more wins, the same count is a tie. Empty squares left at the end do not count for anyone. With 64 squares, 33 discs is a sure win.

Tips

1. Corners are gold. A disc in a corner can never be flipped, and it makes the discs along its edges safe as well. Take a corner whenever you can.
2. Stay off the squares next to an empty corner. The square diagonally beside a corner is the worst: it often hands the corner to your opponent.
3. Fewer flips can be better. Early on, a move that flips one disc often beats a move that flips five. Grabbing a lot of discs gives your opponent more targets and more moves.
4. Count moves, not discs. Through the middle of the game, the player with more choices is usually winning. Try to leave your opponent with few good squares, and with luck, none at all, so they must pass.
5. Edges are strong, but not always. A disc on an edge can only be flipped along that edge. Be careful, though, about leaving a gap your opponent can slip into next to a corner.

Today's opening

The Daily Opening starts everyone from the same position: the first two moves for each side are already on the board. You play Black against the same computer player as everyone else. The more discs you finish with, the better, and you can see how you compare. Your first try of the day is the one that counts.

Questions

Is this the same game as the one with the green board I know from a box? Yes. That boxed game uses the same board, the same starting position and the same rules. Reversi is the older, generic name.

Do flipped discs flip other discs too? No. Only the lines trapped by the disc you just placed flip. A disc that turns over does not start a chain of its own.

What happens to empty squares at the end? Nothing. Only the discs on the board are counted. Some families give the empty squares to the winner. We may add that as an option later.

How strong is the computer? Easy grabs whatever flips the most, which is how most people start, and sometimes plays at random. Normal thinks a few moves ahead and knows about corners. Sharp looks much deeper and plays the last dozen moves perfectly.

Can two people play on one phone? Yes. Choose "Two on one device", sit across from each other and pass the phone.

Can I turn off the dots? Yes, in Settings. The Hint button still shows a good move when you want one.

Do I need an account? No. Your game is saved in this browser, so you can close the page and come back.