Reversi

Reversi rules

• The board has 64 squares. The game starts with four discs in the center: two black and two white, placed diagonally.
• Black moves first, then the players take turns.
• On your turn, place one disc of your color on an empty square so that at least one straight line of your opponent’s discs lies between your new disc and another disc of yours. The line can run across, up and down, or diagonally, with no gaps.
• Every opposing disc trapped this way flips to your color. One move can flip lines in several directions at once.
• A move that would flip nothing is not allowed. If you have no legal move, you pass and your opponent plays again. You can never pass if you have a move.
• The game ends when neither player can move, usually because the board is full. The player with more discs on the board wins. Equal counts are a draw.

How to play on this page

1. Open Setup and choose who you play against: Computer, Friend online, or 2 players, one device. Friend online gives you a link to send, and each of you plays on your own screen.
2. Against the computer, pick Easy, Medium or Hard, and decide whether to play Black and move first, or White and move second.
3. Small dots show every square where you can play. Click or tap one to place your disc, and watch the trapped discs flip.
4. The counts beside each player show how many discs they have right now. The last move is highlighted on the board.
5. If someone has no legal move, the page says so and the other player goes again. You don’t need to press anything.
6. Undo takes back your last move, together with the computer’s reply. Your settings, score and the game in progress are saved in this browser.

Tips for winning

• Take the corners. A disc in a corner can never be flipped, and it gives you safe lines along both edges.
• Avoid the squares right next to an empty corner, especially the diagonal one. Playing there often hands the corner to your opponent.
• Don’t chase a high count early on. Flipping many discs in the opening usually gives your opponent more moves and you fewer.
• Keep your options open. The player with more possible moves can wait for a good one, while the other may be forced into a bad one.
• Prefer quiet moves that flip few discs and leave your discs surrounded rather than touching empty squares. Discs on the edge of the crowd are the easiest to flip.
• Near the end, count. With only a few squares left, the order you fill them can decide the game, and sometimes making your opponent pass is worth more than any single flip.

Frequently asked questions

Do I need to download anything or sign up?

No. The game runs in your browser on a computer, tablet or phone. There is nothing to install and no account to create.

What happens if I have no legal move?

You pass, and your opponent plays again. The page tells you when this happens and plays on by itself. If neither player can move, the game ends right away, even if empty squares are left.

Can the game end before the board is full?

Yes. If neither side can place a disc that flips anything, the game is over and the discs are counted. It can even end early when one player loses every disc.

Who moves first?

Black always moves first. Against the computer you can choose to play Black or White, so you can practice both sides.

How strong is the computer?

Easy plays casually and often misses good moves, which makes it a good place to learn. Medium looks a few moves ahead and knows the value of corners. Hard searches much deeper, plays the last part of the game perfectly, and will punish small mistakes.

Will my score be saved?

Yes. Your settings, your score and the game in progress are saved in this browser, so they will still be here when you come back. They are not sent anywhere, and clearing your browser data removes them.