Reversi (Othello) rules: flipping discs, when to pass

Reversi (in its branded version, “Othello”) is a game played on an 8×8 board with two-sided discs: one side black, the other white. There are only a handful of rules, but they are exactly what raises questions: how many discs you flip per move, whether you can place a disc anywhere, what to do when there's nothing to play, and who wins if a player can't move. Let's work through each one by the rules, with board examples.

In short: the key answers

You flip ALL the flanked discs, not just one. On a single move you flip every opponent disc that ends up trapped between your discs — and in every direction where such a flank exists at once.
You can only place a disc that flips something. A disc goes only on a square where it flips at least one of the opponent's discs. A move “for nothing,” with no flip, is not allowed.
Nothing to play — you pass. If you have no legal moves, the turn passes automatically to your opponent. But if you do have a move, you can't pass — you're required to play.
The majority of discs wins. When NEITHER player can move, the game is over: you count the discs, and whoever has more of their own color wins.

Starting position and goal

In the center of the 8×8 board, four discs stand crosswise: two black and two white, set diagonally. Black moves first. The goal is to have more discs of your color on the board when the game ends.

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Starting position (center of the 8×8 board): two black and two white discs set crosswise on the diagonal. Black moves first.

How many discs to flip: all or one

The main question for beginners. The answer: you flip all of the opponent's discs that end up trapped between the disc you just placed and any disc of yours already on the board — along a straight line (horizontal, vertical, or diagonal), with no gaps. Not one disc, but the whole flanked line.

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Black places a disc on the left (in the gold frame). Three white discs end up flanked between the new disc and the black disc that was already on the right — all three flip at once, not just one.

Flipping happens in every direction at once

If the disc you place flanks the opponent's lines in several directions at the same time, all of those lines flip on a single move. The black disc in the corner below flanks the white discs along the horizontal, vertical, and diagonal all at once.

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A single black disc (in the frame) flanks white discs along the row, the column, and the diagonal at once — every flanked disc flips on that same move.

When there's nothing to flip

You can place a disc only where it flips at least something. A square that flanks none of the opponent's discs is an illegal move — you can't play there.

If a legal move exists, you must play. You can't pass by choice: if there is even one flipping move, you have to make it.
No moves — you pass. Only when there isn't a single square left to flip does the turn pass automatically to your opponent. You place nothing and flip nothing.

A “quiet” move is often stronger

Flipping as many discs as possible per move is usually a bad idea: a modest move that changes one or two discs keeps better control of the center and edges. Reversi isn't about being in the majority the whole time.

Who wins if a player can't move

A single pass isn't the end: the opponent may still have something to play, and the game continues. The game ends only when neither player can move (usually when the board is full or locked up).

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The game is over — nobody has a move. You count the discs: black has a clear majority, so black wins. If it's even (32 each), it's a draw.

So in the situation “one move is left, but the player can't make it because it closes nothing off,” the turn simply passes to the opponent; and once nobody can move at all, whoever has more discs wins.

Frequently asked questions

In reversi, do you flip all the discs or just one?

All of them. On a single move you flip every opponent disc trapped between your new disc and a disc of yours already on the board, along a straight line — and in every direction where such a flank exists. You flip only a single disc when exactly one disc is flanked.

How do you move in reversi when there's nothing to flip?

You don't — that move is illegal. A disc can go only on a square that flips at least one of the opponent's discs. If you have no flipping move at all, you pass, and the turn goes to your opponent.

Who wins if a player can't make a move?

First you check the opponent: if they have something to play, the game continues and the “stuck” player simply passes. When nobody can move anymore, you count the discs — whoever has more of them on the board wins. If it's tied (32 to 32), it's a draw.

Can you place a disc anywhere you like?

No. You can place a disc only where it flanks a continuous line of the opponent's discs, closed off by a disc of yours already on the board. Squares that flip nothing aren't available for a move.

Can you pass your turn by choice?

No. If you have at least one legal move, you're required to play it. A pass happens only when forced — when no flipping moves are left at all.

What's the difference between reversi and Othello?

They're essentially the same game. “Othello” is a registered trademark with a fixed starting position (four discs crosswise in the center) and an 8×8 board. Classic reversi historically allowed free placement of the first discs, but today almost everyone plays by the Othello rules.

Who moves first in reversi?

Black moves first. After that the players alternate; when a player has no legal move, they are forced to pass, and the turn goes to the opponent.

Can you play reversi against a bot for free?

Yes — on muta.pro you can play reversi online for free and without registration, against a bot with a choice of difficulty or with a friend by room code.

Check the rules at the board

Now the key points are clear: you flip all flanked discs in every direction at once, you can play only where something flips, no move means you pass, and the majority wins. Lock it in with practice: play reversi online on muta.pro for free against a bot or a friend. A full breakdown of all the rules is on the reversi rules page.