The Story
Where it came from, and why it turned out this way.
StandardizedGoro Hasegawa · Japan, 1971 · from 1880s English Reversi
Invented twice, named once
A disc-flipping game called Reversi appeared in England in the 1880s, with both Lewis Waterman and John W. Mollett claiming to have invented it — a dispute never actually settled. What turned it into the game played today was the work of Goro Hasegawa in Japan: in 1971 he fixed the 8×8 board and the four-disc opening cross, removed the original's free placement of the first four discs, and gave the result the name Othello.
The name comes from Shakespeare
Othello is named for Shakespeare's play, where the relationship between the Moorish general and his white wife was borrowed as an image for a board of black and white discs endlessly flipping. By Hasegawa's own account the name owed something to his father, a scholar of English literature. A game derived from an English original, standardized in Japan, and named for an English tragedy is an unusual pedigree in itself.
Why a middlegame lead means nothing
The most counter-intuitive thing about Othello is written into its rules: discs are counted only at the final moment. Having more discs in the middlegame is usually bad, because more discs means more frontier discs, and frontier discs are exactly where your opponent's moves come from. The real resources are mobility and stability — the first measures how many options your opponent has left, and the second is the only lead that can never be flipped away.
Forty years of being calculated out
An 8×8 board sits right inside the reach of computers. In 1997 Michael Buro's program Logistello swept the reigning world champion Takeshi Murakami 6–0, and the human-machine gap never narrowed again. In 2023 a computational effort announced that 8×8 Othello had been weakly solved: with perfect play by both sides, the game is a draw. A game won by flipping discs turns out to have equality as its final answer.
- Endgame parity is the game's most distinctive technique: 60 empty squares at the start mean that with no passes the final move belongs to White, and every pass flips that relationship.
- The four corners are the only naturally stable squares on the board, which makes the adjacent X-squares and C-squares the recognized danger zone — that vocabulary is essentially the shared language of Othello players.
- Hasegawa promoted the game for the rest of his life; the Japan Othello Association was founded in 1973 and the first World Championship was held in Tokyo in 1977.
Complete Rules
Start with what a turn allows and how the game is won.
- Board
- 8 × 8, 64 squares
- First move
- Black, with only four legal openings
- Winning conditionwhen the game ends, count the disks on the board; whichever color has more wins, and an equal count is a draw. The game starts with two black and two white disks in the center, Black moves first, and play alternates.
- A placement must bracket enemy disks: between your newly placed disk and one of your existing disks, along a horizontal, vertical, or diagonal line, there must be an unbroken run of enemy disks, and all of them flip to your color. There can be no gap in the run, and you cannot bracket your own disks.
- A single move can be valid in as many as eight directions at once, and every bracketed disk must flip. You may not choose to flip only some of them.
- An empty square that flips nothing is not a legal move. As long as you have any legal move you must play — you cannot voluntarily give up your turn.
- If a player has no legal move at all, they must pass and their opponent continues. Passing is not a loss, and the interface handles it automatically, so your opponent may end up playing several moves in a row.
- The game ends immediately when both players have no legal move in succession. This can happen while the board is still far from full, and the remaining empty squares belong to nobody.
- The final score compares only the actual number of black and white disks on the board. There are no captures at any point — flipped disks stay on the board — so how many disks you flipped along the way has no bearing on the final score.
- Disks never move once placed. Every change in the position comes solely from adding one new disk and flipping the disks it brackets.
Your First Game
Use this order of thought to get through a complete game quickly.
- Black's opening has only four legal squares — C4, D3, E6, and F5 — and they are rotations of each other, so all four are exactly equivalent. Real divergence starts only on the second move.
- Take corners above all else. A1, A8, H1, and H8 cannot be bracketed from any side, so a disk on a corner can never be flipped again. They are the only naturally stable squares on the board.
- Memorize two dangerous square groups. The X-squares are B2, G2, B7, and G7 — the diagonal neighbors of the four corners. The C-squares are A2, B1, G1, H2, A7, B8, G8, and H7 — the two edge squares adjacent to each corner.
- Do not occupy an X-square while the corner beside it is still undecided: your own disk there provides the far end of a diagonal bracket through the corner, which is effectively handing the corner over. C-squares invite your opponent to wedge into that edge, and lose the corner just as reliably.
- In the middlegame, prefer the move that flips the fewest disks. Flipping less means fewer of your disks touch empty squares, which means fewer directions your opponent can bracket from.
- Before every move, count how many legal moves your opponent will have after you play. Shrinking that number is far more useful than growing your own disk count.
- When you are unsure, play inside the central 4 × 4 block of sixteen squares and leave the edges alone until the position clarifies.
Practical Strategy
Move from knowing the rules to playing with a plan.
- Mobility is the central theme: work to reduce your opponent's legal moves until they can only play bad squares that give up a corner or an edge — or until they must pass entirely.
- The few-disks strategy is the companion of mobility: keeping your own disk count low, your disks clustered, and your position near the center usually preserves your options while squeezing your opponent's.
- A frontier disk is one of your disks adjacent to at least one empty square, and frontier disks are exactly where your opponent's moves come from. The fewer frontier disks you have, the fewer directions they can play in.
- A stable disk is one that no future move can ever flip. Corners are stable by nature; an unbroken run of your color running along an edge from a corner is stable too; and disks on a completely filled row, column, or diagonal are also stable. Edge disks with no corner behind them are not safe.
- Only the number of stable disks can never decrease during the game, which is why stability is the one lead you can actually accumulate. A middlegame disk advantage can be flipped away by your opponent's very next move.
- Paritythe game starts with 4 disks and 60 empty squares, so if nobody ever passes, Black plays moves 1, 3, … 59 and White plays move 60 — the last move naturally belongs to White. Each pass flips this parity relationship.
- In the endgame, treat regions of non-adjacent empty squares separately: keep an even number of squares in any region where you want the last move, because taking the final move inside a region often flips an entire edge back in one stroke.
- When your opponent has to pass you get consecutive moves, which is the easiest chance in the game to rewrite a whole edge or seize a corner. It is worth engineering several moves in advance.
Winning and Special Rules
Details that are easy to miss but can change the result.
- Having no legal move forces a pass; this is part of the rules, not a losing condition. Two passes in succession end the game, and the board may still have empty squares at that moment.
- The final score is the disk count on the board. This site does not award the leftover empty squares of an early finish to either side — it simply compares the disks actually present.
- Once few enough empty squares remain, the AI switches to exact solving and computes the final disk difference outright. In that phase a single disk can decide the game.
- The interface marks every legal move, shows how many disks each would flip, and handles passing automatically. Disks never change position after they are placed.
Common Mistakes
The traps new players fall into most often.
- Treating a middlegame disk lead as an advantage. From the opening into the middlegame, having fewer disks is usually better, because it generally means more mobility and fewer frontier disks.
- Playing an X-square or C-square before the corner beside it is settled, and handing A1, H1, A8, or H8 straight to your opponent.
- Grabbing a move that flips a lot of disks and ending up with your own disks spread across the frontier, so your opponent can play almost anywhere next turn.
- Checking only one bracketing direction and missing the flips the same move produces in other directions, which distorts your read of the whole position.
- Believing that filling an entire edge makes it safe. Edge disks without a corner behind them can still be flipped in one stroke from the far end of that edge.
- Thinking that having no legal move means you lose, or that the board must fill completely before the game ends.