How to play Othello

Two players, one set of two-faced discs, and a board that changes hands until the last square is filled.

Players: 2
What you need: A board of 64 squares and 64 discs, black one side and white the other
How long: A game takes a few minutes

What Othello is

Othello is a game for two on a board of sixty four squares. The two of you share one set of discs, black on one face and white on the other, and the face showing is whose disc it is for now.

A move puts a disc down so that it closes a straight line of your opponent’s discs between it and another of yours. Every disc in that line turns over and becomes yours.

When nobody can play any more, whoever has more discs showing wins. A game runs about sixty moves and rarely ends the way it looked halfway through.

Every disc is black on one face and white on the other, so the board changes hands all game.

The board

Eight squares by eight, ruled in plain lines. Four dots are printed two squares in from each corner. They carry no rule at all and are there to be counted from.

Four discs start in the middle, laid crosswise. Black takes the two squares of one diagonal and white takes the other two, which is why black has exactly four opening moves and all four are the same move turned round.

The opening position. Black moves first.

Setting up

Put the board between you with the ruled side up.
Lay four discs on the four middle squares, crosswise, so each colour has one square of each diagonal.
Black moves first. Here, the colour you pick on the game page is yours for the first game and the two of you swap after it.
Keep the rest of the discs where both of you can reach them. Nobody owns a disc in this game, only a face.

Taking a turn

On your turn you put one disc, your face up, on an empty square. The square has to close a line.

Closing a line means this. Start at the square you are playing, walk out in a straight line in any of the eight directions, step over one or more of your opponent’s discs, and arrive on one of your own. Every disc you stepped over turns to your colour.

Black plays the top square and closes the two white discs against the black one below them.

One move can close several lines at once, and all of them turn. A move that closes nothing is not a move at all, so a square with no line to close is a square you may not play on.

On a screen the squares you may use carry a small dot. Tap one and the disc goes down, then the lines it closed roll over after it.

Black’s four opening moves. Each one closes a line of a single white disc.

When you cannot move

Sometimes no square on the board closes a line for you. When that happens you lose the turn and your opponent plays again.

You are not asked about this and there is no button for it. A turn with one possible outcome is not a decision, so the game plays it and the rail says whose turn went.

Losing a turn is not always bad news. A player with few discs often has more places to put them, and squeezing an opponent until they run out of squares is one of the ways this game is won.

How a game ends

The game ends when neither side has a move. Usually that is because every square is covered, and the count is simply the discs.

It can also end early, with squares still empty, when both sides are stuck. One side losing every disc ends it too, which is rare and sudden.

If the board does not fill, the empty squares go to whoever is ahead, so the two scores add to sixty four. You can turn that off on the game page and count only what is on the board. The same side wins either way.

Most games end with the board full and a count.

Why the corners decide it

A disc turns by being closed between two of the other colour. A corner has nothing at all on two of its sides, so a corner disc can never be closed and never changes hands.

That makes the four corners worth more than anything else on the board. It also makes the square diagonally inside an empty corner the worst square there is, because putting a disc there is usually what hands the corner over.

The same reasoning runs along the edges. A whole edge anchored to a corner is safe, and safe discs are the only discs that count at the end.

A disc in a corner can never be closed, so it never turns again.

Playing here

The rail above the board says whose turn it is. Below it sits the number of squares still empty, and the two disc counts are in the rail at the foot.

Your legal squares carry a small dot. Tap one to play. There is nothing to drag and nothing to pick up, because a disc never moves once it is down.

The disc you just played is ringed, and the discs it turned are marked with it, so the other side’s move can be read after it has happened.

Watch mode sets two bots against each other and deals another game when one ends. It is the quickest way to see what a sound opening looks like.

Playing better

Take a corner whenever one is offered. Very little else is worth as much.
Avoid the square diagonally inside an empty corner. That is how corners are given away.
Turning the most discs is usually the worst move on the board. A big turn spreads your colour along the edge of the empty ground, where your opponent can take it all back.
Count your moves rather than your discs. Being well ahead halfway through a game means very little.
Try to be the one playing the last few discs. Late moves turn long lines and there is no time left to answer them.

Settings

Everything on the game page, before you press Play.

Setting	Standard	What it changes
Mode	Play	Watch sets two bots against each other and starts a fresh game when one ends.
Your colour	Black	Black moves first, which is a small edge. The colours swap after every game.
Difficulty	Medium	How far ahead the bot looks, and how exactly it plays the last dozen moves. Easy throws moves away on purpose.
Empty squares count	For the winner	What an empty square is worth when a game ends before the board fills. It changes the score, never who won.
Speed	Normal	How quickly the discs turn. It does not change how well the bot plays.

The words

Othello: The name the game has been sold under since 1971. The rules are a good deal older.
Reversi: The older name for very nearly the same game. In old Reversi the players chose where the first four discs went.
Disc: One piece. Black on one face and white on the other, so it belongs to whoever played it last.
Turn: What happens to a closed line. It is the only thing that ever happens on this board.
Corner: One of the four squares that can never be closed, and so never turns.
Edge: The outer ring of squares. Hard to turn, and safe once it reaches a corner.
Mobility: How many squares you may legally play on. Having more of them than your opponent is worth more than having more discs.
Pass: Losing a turn because no square closes a line for you.
Wipeout: Losing every disc on the board, which ends the game on the spot.
Safe disc: A disc that can never be turned again. Only safe discs are really yours.

Every rule on this page is the one the app plays by. Change any of them on the game's own page before you start.