Reversi
NEWWorks on both desktop and mobile. Tap or click to play.
About This Game
Play Reversi free online against the computer - the classic disc-flipping strategy game. Outflank your opponent to own the most discs. Easy to Hard AI.
How to play Reversi
Objective: Finish the game with more discs of your color on the 8x8 board than the computer, since the count at the end decides the winner.
You play black, the computer plays white, and the board starts with four discs already placed in the center. Black moves first. On your turn the squares where you can legally play are marked with small translucent dots, so you never have to guess. A move is legal only when placing your disc traps one or more unbroken lines of white discs between the disc you just laid and another black disc you already own.
Tap a dotted square to drop your disc. Every white disc caught in a straight line between your new piece and an existing black piece flips to black immediately, and lines flip in all eight directions at once from the same move. The running score above the board updates the moment you play: the black count is you, the white count is the CPU. After you move the computer takes its turn after a short pause.
If you have no move that flips at least one white disc, your turn is skipped automatically and the other side plays again. The same rule applies to the computer. When neither side has a legal flip anywhere on the board the game ends, even if empty squares remain. This is why the board does not always fill completely before a result is shown.
At the end the discs are counted. More black than white shows a win message, fewer shows the computer wins, and an equal split is a tie. A win only counts toward your saved Wins total when you finish ahead. Pick Easy, Medium, or Hard before or during a session; changing difficulty starts a fresh game with the center opening again.
Tips and strategy
Grab the corners
The AI values corner squares at 120 points, the highest on the board, because a corner disc can never be flipped. Steer play toward taking corners yourself, and treat every corner you win as a permanent anchor for flipping long lines later.
Avoid X and C squares
The three squares next to each empty corner carry heavy negative weights (-20 and -40 in the AI's table). Playing them hands the computer the corner. Hold off on the diagonal-adjacent square until the corner is already settled.
Flip fewer, not more
Taking the most discs early backfires. A big lead mid-game gives your opponent more edge squares to flip back. Prefer quiet moves that keep your pieces on stable edges over greedy captures that expose your center to recapture.
Starve its moves
The AI adds four points per extra move it has over you, so limiting its options hurts its score. Play so the computer is forced onto squares next to corners, or into a forced pass, and its evaluation collapses.
Beat Hard with patience
Hard searches five moves deep and plays the exact best line, while Easy searches one move and adds random noise. Against Hard, plan corner control from the opening rather than reacting move to move, since it punishes any square you give up near a corner.
The history of Reversi
Reversi dates to 1880s England, where two rival inventors, Lewis Waterman and John Mollett, each claimed the game and disputed its authorship. It was sold commercially under the Reversi name and settled into the eight-by-eight board with the crossed four-disc opening still used here.
In 1971 the Japanese salesman Goro Hasegawa marketed a near-identical game under the trademark Othello, borrowing the play's black-and-white rivalry for the name and fixing the standard starting position. The two names now cover the same game, which became a staple of early computer AI research because its rules are simple but its strategy, especially corner control, runs deep.
Frequently asked questions
Which color do I play and who goes first?
You always play the black discs and the computer plays white. Black moves first every game, matching standard Reversi. The opening board has two black and two white discs crossed in the center four squares, so your very first move must flip at least one of the two white starting discs.
Why are some squares dotted?
The translucent dots mark your legal moves for the current turn. A square is legal only if dropping a disc there traps at least one straight line of white discs between your new piece and another black piece you own. Squares with no dot cannot be played, so tapping them does nothing.
What do the three difficulty levels change?
Difficulty sets how far ahead the computer looks. Easy looks one move ahead and mixes in random noise, so it sometimes plays loose. Medium looks three moves ahead. Hard looks five moves ahead and always picks its best evaluated line, making it far harder to trap near the corners.
Can my turn be skipped?
Yes. If you have no move anywhere that flips a white disc, your turn passes automatically and the computer plays again. The same happens to the computer when it is stuck. When neither side can move the game ends and the discs are counted, even if the board is not full.
Does the game save my wins?
It keeps a running Wins count shown above the board, stored only in your own browser. The counter goes up by one each time you finish with more discs than the computer. Ties and losses do not add to it, and clearing your browser data resets the total to zero.
Is there a clock or move timer?
No. There is no timer, no lives, and no move limit. You can take as long as you want on each turn. The only pause is a short delay before the computer replies so you can see the board update. Games end purely by both sides running out of legal moves.