Look for an available corner
A takes the corner and flips one white disc. A corner cannot be flipped back and can anchor future connections.
Black to move
Small dots mark the moves you can play.
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Standard · 30s/move
Black
YouRunning
This moveThis move
White
ComputerWaiting
Next moveThis move
Black · Time left for this move
Arrow keys to move · Enter or Space to play
Last move (square) · Empty-cell dots mark legal movesReversi rules and strategy
New here? Start with the essentials. Otherwise jump to a diagram or strategy.
Start with these rules
- Place where you can trap opposing discs
Black starts. A continuous line of opposing discs must lie between your new disc and one you already have.
- Flip every trapped line
Check all eight horizontal, vertical and diagonal directions. One move can flip several lines.
- When neither can move, compare the final counts
A player without a move passes automatically. When neither can move, more discs wins; equal counts draw.
See it on the board
Close both ends to flip the middle
Black at A traps both white discs between the new and existing black discs, so both flip. A gap would break this capture.
A marks the stone placed in this diagram. An enlarged part of the full board.
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Flipping example: empty, White, White, Black
If a row reads empty, White, White, Black from left to right, Black can play at the empty end and flip both white discs. Empty, White, empty, Black cannot capture along that line because of the gap.
If the new disc captures along both a row and a diagonal, both lines flip. Flipped discs do not trigger further chain captures: only straight lines from the newly placed disc are checked.
Three strategies to learn first
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Why a corner is safe once taken
A corner cannot be surrounded from both ends along any line without going outside the board, so its disc cannot be flipped. Use an owned corner to plan connections that can survive to the end.
Be careful with a cell diagonally next to an empty corner. If your disc sits there and an opposing disc lies further along the diagonal, the opponent may take the corner and capture yours. Such cells are not always bad, but check that capture route first.
Look at the next choices, too
The small blue rings are Black’s four legal moves. Compare the moves you open for the opponent, as well as the discs you flip now.
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Strategy: compare future moves, too
Flipping many discs early may look strong while opening new moves for the opponent. Compare not only the discs you gain now, but the moves your opponent will have next.
Try to keep your options while limiting theirs. Simply minimizing their number of moves is not always best: their one remaining move might take a corner. Consider the quality of those cells.
Count the discs that will remain at the end
This full-board example ends 40–24 for Black. With few empty cells, consider replies and passes to compare final counts.
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Endgame practice: count moves and passes
With few empty cells left, examine each possible reply. An opponent’s pass lets you move again; if both cannot move, the current counts decide without filling the remaining cells.
For example, a finished position with 30 black discs, 28 white and six empty cells is a Black win here. Empty cells are not awarded to either side. Look for the largest final count, not merely the largest flip now.
More questions
Full rules and starting your first game
Reversi rules: the final disc count decides
Start with two black and two white discs in the middle of an 8×8 board, with matching colors diagonally opposite. Black starts. You may place a disc only if it flips at least one opposing disc.
A continuous line of opposing discs between the new disc and an existing disc of your color is flipped. Check all eight horizontal, vertical and diagonal directions, and flip every captured line. Existing discs are not moved to another cell.
Find a legal cell first
Choose the computer for solo play or two players on the same screen. From an empty cell, look for a straight line of opposing discs ending at your own disc. At least one opposing disc must be captured.
- Check each of the eight directions from the empty cell.
- Look for an adjacent opposing disc followed by more opposing discs and then your own.
- A gap or the board edge breaks the capture. An adjacent disc of your own color does not capture anything in that direction.
- Place your disc on a legal cell, then check the flipped discs, counts and next turn.
Passes, endings and consecutive turns
Passes and endings can happen before the board is full
A player with no legal move must pass. This game handles that automatically. You may not choose to pass when a legal move exists. One player can therefore take several consecutive turns.
When neither player can move, the game ends even with empty cells. The color with more discs on the board wins; equal counts draw. A lead during play is not the final result.
FAQ: why is it my turn again?
Your opponent may have passed automatically because no legal move was available. Turns do not always alternate one for one. If both players have no move, the result is calculated.
If clicking an empty cell does nothing, check that it captures in at least one direction. Being next to an opposing disc is not enough; your own disc must close the other end.
Am I behind if I have fewer discs?
FAQ: am I losing if I have fewer discs?
The result is decided only at the end. Current counts are a reference; corners and better future options may allow a comeback. The computer is also not a perfect solver of every board.
Local two-player mode shares one device and can help you explain moves and flips to one another. Remote random matches and friend rooms are a separate online mode available when the service is configured; there are no public rankings.
Clocks and move sounds
Clocks and move sounds
Play without a per-move or total time limit. There is no loss on time. Choose a fresh time limit per move, a total budget for each player, or both. Total time runs only on your own turn. With both limits, the first to expire loses the game; unused move time is not added or carried over. The computer follows the same limits while calculating.
Presets: Blitz · 15s/move / Standard · 30s/move / Long · 60s/move. These are casual settings for this site, not universal tournament time rules. The clock starts with a new game and is not reset by leaving the tab or refreshing. Undo restores the clock balances from before that move. Enter your total time separately from the per-move presets. 10 or 10:00 means 10 minutes; 5:30 means 5 minutes 30 seconds. Combined mode uses the same custom total.
Reversi uses a lower disc-contact sound with a light flipping sound. Many flips are limited to avoid excessive overlap. You can turn sound off; it plays only for legal moves.
Online play: random opponents and friend invites
Online play: random opponents and friend invites
When the online service is configured, guests can find a random opponent or join a friend room without accounts or nicknames. The server assigns colors. There is no free chat or public ranking.
Random matching waits up to two minutes and needs another connected player. Friend invites expire after ten minutes if nobody joins. Share the code or invite link with your intended opponent.
Both online modes use 30 seconds per move, no undo and a maximum two-hour game. Moves are final only after server validation. Confirm resignation before leaving an active game or choosing another mode. The clock keeps running during disconnects: the 60-second return grace does not extend the move limit. The same tab’s saved secret can restore a session; blocked or cleared storage may prevent return after a reload. Offline time options remain separate.
Try a different kind of board
Try Gomoku and be the first to complete a line.
Play Gomoku