Reversi
Reversi, best known as Othello, is the game of black and white discs that flip. Trap a line of your opponent's discs between two of your own to turn them over, and finish with more discs of your colour than the other side. Play the computer from Easy to Hard, a friend on the same screen, or watch the computer play itself. Click a marked square to place a disc and flip the discs it traps. Hover over a square to see which discs would flip. If you cannot move, you pass. Undo takes back a move.
How it works
- Choose a mode: play the computer as Black or White, play a friend on the same screen, or let the computer play both sides.
- Click one of the marked squares to place a disc. Hover over a square to see which discs it would flip. If you have no move, you pass.
- The game ends when neither side can move, and the side with more discs wins. Undo takes back a move and the move list keeps the score.
How to play
The game starts with two black and two white discs crossed in the centre, and Black moves first. You place a disc so that one or more straight lines of your opponent's discs, across, down or diagonal, are trapped between the new disc and another of yours. All the trapped discs flip to your colour. A move must flip at least one disc.
Passing and the end of the game
When you have no move that flips a disc, you must pass and your opponent moves again. The game ends when neither side can move, usually because the board is full. The discs are counted and the side with more wins; the same number is a draw.
Tips for a better game
Corners can never be flipped, so they are the most valuable squares. Avoid the squares right next to an empty corner, which often give it away. Early on, having fewer discs and more possible moves is usually better than grabbing many discs, and discs on the edges become stable once a corner is taken.
Frequently asked questions
How strong is the computer?
Easy looks two moves ahead and makes mistakes. Medium searches five moves deep and plays the last ten empty squares perfectly. Hard thinks for about two seconds a move and plays the last fourteen squares perfectly, which makes it a real challenge.
What happens if I cannot move?
You pass and your opponent moves again. The board tells you when this happens. When neither side can move, the game is over.
Can I play against a friend?
Yes. Choose Two players and take turns on the same screen.
Can I watch the computer play itself?
Yes. Choose Computer against computer. The Speed slider sets how fast it moves, and Pause stops the game so you can look at the position.
Is it free?
Yes. It is free, runs in your browser and needs no sign-up. You can also save the board as a PNG.
Related tools
About Reversi - History, Rules, Othello and Computers
A short guide to Reversi and Othello: the game invented in London in 1883, Goro Hasegawa's Othello of 1971, the rules, strategy, Logistello's 1997 victory and the 2023 proof that the game is a draw.
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